Patent Publication Number: US-2023161671-A1

Title: Systems and methods for host image transfer

Description:
RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 16/873,964, which was filed on Aug. 28, 2020; which is a continuation of U.S. patent application Ser. No. 15/677,704, which was filed on Aug. 15, 2017 and issued on Sep. 1, 2020 bearing U.S. Pat. No. 10,761,947; which is a continuation of U.S. patent application Ser. No. 15/176,800, which was filed on Jun. 8, 2016 and issued on Aug. 15, 2017 bearing U.S. Pat. No. 9,734,019; which is a continuation of U.S. patent application Ser. No. 14/796,632, which was filed on Jul. 10, 2015, and issued on Jun. 14, 2016 bearing U.S. Pat. No. 9,367,404; which is a continuation of U.S. patent application Ser. No. 13/909,843, which was filed on Jun. 4, 2013 and claims the benefit of U.S. Provisional Patent Application No. 61/655,308, which was filed on Jun. 4, 2012; all of which are assigned to the assignee of the present invention and are incorporated by reference herein. 
     The present application is related to U.S. patent application Ser. No. 17/157,053, which was filed on Jan. 25, 2021; U.S. patent application Ser. No. 13/909,746, which was filed on Jun. 4, 2013, and issued on Sep. 11, 2018 bearing U.S. Pat. No. 10,073,745; and U.S. patent application Ser. No. 16/123,812, which was filed on Sep. 6, 2019; all of which are assigned to the assignee of the present invention and are incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     Data recovery and, more particularly, automated data recovery from any type of client machine to any type of recovery machine, and failover back to any type of client machine. 
     BACKGROUND OF THE INVENTION 
     Ensuring smooth recovery of operations after downtime due to data loss or corruption, equipment failure, or complete site outage after a power loss, a natural disaster, such as an earthquake, a flood, a hurricane, or a tornado, for example, or a man-made problem, such as a spill of hazardous material, infrastructure failure, or sabotage, for example, is a significant challenge to data centers. Resuming operation at a data disaster recovery site, whether planned (such as a scheduled site migration) or unplanned (such as an accidental event), requires careful preparation. Planning for such contingencies could take months, while the execution of the plan may need to take place in minutes. Dozens or hundreds of steps need to be performed by the application, hardware, network, and storage teams. Any error, process flaw, routing issue, or other factors could delay the site recover. 
     To separate the site from the same risks posed to the client system, the remote disaster recovery site may be separated from the client system by many miles. The disaster recovery site may be in a different part of a city, a different city, a different state, a different country, or even a different continent than the client system, depending upon the risks to the client system and the budget of the client system, for example. This lessens the risk that a power failure, natural disaster, or man-made problem at the client system is also affecting the disaster recovery site. 
     The servers, desktop computers, laptop computers, and workstations at a client are referred to as client machines, while the servers, desktop computers, laptop computers, and workstations at a data recovery site are referred to as recovery machines. Client machines and recovery machines may be physical or virtual. The data images and unpersonalized operating system (“OS”) installed on disks of machines before purchase are referred to as an OS Image. The OS Image is personalized and turned into a host image for that machine, on startup. Applications may then be installed, data may be created, and the machine further customized. After the machine is configured and used, the OS and Data Images stored on a hard drive of a machine are referred to as a host image. In disaster recovery, a backed up copy of the host image is typically recovered to a recovery machine so that the host image may run on the recovery machine. 
     The known commercially available disaster recovery solutions have limitations. Some known commercially available conversion processes require a pre-configured destination machine or machines with the same hardware and/or operating system (“OS”) as the client machine, which adds significant cost and is slow. Others require that software be written to handle recovery to a predetermined type of recovery machine. 
     Site Recovery Manager, available from VMware, Inc., Palo Alto, Calif., for example, only enables recovery of applications running in virtual machines hosted on VMware ESX server by hypervisor. It is not possible to move a host image running on a failed physical machine to a virtual recovery machine and back to the physical machine or to another physical machine during failback from the disaster recovery data center back to the client system. Citrix Systems, Inc., Fort Lauderdale, Fla., has a similar product with similar limitations. Windows® Server 2008 R2 Failover Clustering, an adaptation of Microsoft Cluster Service (MSCS), available from Microsoft Corporation, Redmond, Wash., allows supported applications to be clustered. This is a high availability solution that requires the cluster machines at the disaster recovery site to be up and running 24/7, in anticipation of a disaster. This can be quite expensive. The active cluster machines at the disaster recovery site require power, licensing, and maintenance. 
     RecoverTrac 2.0, available from FalconStor, Inc., Melville, N.Y., enables automatic recovery from a physical client machine to a physical recovery machine (physical-to-physical (“P2P”) recovery), as long as the two physical machines are of the same type (same type of hardware, same manufacture, and same operating system). RecoverTrac 2.0 also enables automatic recovery from a virtual client machine to a virtual recovery machine (virtual-to-virtual (“V2V”) recovery), and from a physical client machine to a virtual recovery machine (physical-to-virtual (“P2V”) recovery), for any certified hypervisor or physical platform, as long as the type of the client machine and the type of the recovery machine are known to the recovery system. In this case, conversions required to a host image or a recovery machine, including the replacement of storage drivers and the setting of IP addresses, as necessary, are hard coded in the software controlling the recovery process. The software is written based on the type of the client machine and the recovery machine, and their operating systems. Recovery jobs include local data recovery, such as bare metal recovery jobs, as well as remote data recovery, with both site failover and site failback orchestration. 
     In many instances, client machines are old and the same model of hardware is no longer commercially available. The client machines to be recovered are not always known to a disaster recovery site and the recovery machines are not always known to the client system prior to a disaster. 
     SUMMARY OF THE INVENTION 
     Methods and systems for transferring a host image of a first machine to a second machine, such as during disaster recovery or migration, are disclosed. In one example, a first profile of a first machine of a first type, such as a first client machine, is compared to a second profile of a second machine, such as a recovery machine or a second client machine of a second type different from the first type, to which the host image is to be transferred, by a first processing device. The first and second profiles each comprise at least one property of the first type of first machine and the second type of second machine, respectively. At least one property of a host image of the first machine is conformed to at least one corresponding property of the second machine. The conformed host image is provided to the second machine, via a network. The second machine is configured with at least one conformed property of the host image by a second processing device of the second machine. 
     In accordance with an embodiment of the invention, a method of recovering a host image of a first machine to a second machine is disclosed comprising, comparing a first profile of a first machine of a first type to be transferred to a second profile of a second machine of a second type different from the first type, to which the host image is to be transferred, by a first processing device. The first and second profiles each comprise at least one property of the first type of first machine and the second type of second machine, respectively. At least one property of a host image of the first machine is conformed to at least one corresponding property of the second machine based, at least in part, on the comparison, by the first processing device. The host image includes an operating system. The conformed host image is provided to second machine, via a network, and the second machine is configured with at least one conformed property of the host image by a second processing device of the second machine. The second processing device is different from the first processing device. 
     In one example of an embodiment of the invention, a method of recovering a host image of a client machine of a first type to a recovery machine of a second type different from the first type is disclosed comprising, collecting and storing profile information for at least one client machine and at least one recovery machine, and comparing a first profile for a client machine of a first type to be recovered to a second profile of a recovery machine of a second, different type, to which the client machine is to be recovered. The method further comprises conforming properties of a host image of the client machine to the properties of the recovery machine based on the comparison, providing the conformed host image to the recovery machine, configuring the recovery machine based on the conformed properties of the host image during a first, limited boot up, and rebooting the recovery machine in a second, normal mode boot up. 
     The limited boot up may be a safe mode boot up. In some cases, the limited boot is followed by a normal boot, after which the recovery machine may operate as if it were the client machine. In other cases, two limited boot ups are required. A first limited boot up, such as a Windows(R) mini set up, may be provided to replace the hardware abstraction layer (“HAL”) of the recovery machine, and a second limited boot, such as a safe mode boot, may be provided to configure other aspects of the recovery machine. In this case, normal mode boot up may follow the second limited boot up. 
     The properties of the host image that may be conformed to the properties of the recovery machine may include the network storage drivers, the storage adapter drivers, and/or the partition style, for example. The conforming process may be performed by a processing device separate from recovery machine. Additional information required for the operation of the host image on the recovery machine may be provided in a job file. Such information may include configurable information, such as network settings, service settings, geometry settings, and conversion policies, for example. The host image may contain an operating system and the recovery machine may be configured by the operating system on the host image, at least in part during the limited or safe mode boot up. The profiles of the client machines and the recovery machines may be profiles of representative client and recovery machines, for example. 
     The host images may be stored on SAN devices, which may be local backup storage devices of a client system for backing up client machines, and/or remote backup storage devices at disaster recovery systems, which backup the local backup storage devices, for example. Backup of client machines to local backup storage devices, backup of local backup storage devices to remote backup storage devices, and recovery of host images of client machines to recovery machines may take place across one or more networks, the Internet, a wide area network (“WAN”), a local area network (“LAN”), a fibre channel storage area network (“SAN”), an Ethernet, and/or an Internet small computer systems interface (“iSCSI”), for example. In one example, backup of client machines to local backup storage devices may take place across a first network of the client system, such as a SAN, while backup of the local backup storage devices to remote backup storage devices may take place across a WAN. Recovery of host images from client machines and back up from a remote backup storage device to a recovery machine, may take place across a SAN in the disaster recovery system. Recovery to local recovery machines may also be provided, if the local recovery machines are still operational. Failback to the client machines from the recovery machines may also be provided in accordance with embodiments of the invention. 
     In one example of an embodiment of the invention, a system for recovering a host image of a first machine to a second machine is disclosed comprising a first processing device, at least one second machine comprising a second processing device different from the first processing device, and storage associated with the first processing device. The storage stores first profile information for a first plurality of types of first machines including a first type of first machine and second profile information for a second plurality of types of second machines including a second type of second machine different from the first type of first machine. The profile information comprises at least one property of each of the first plurality of types of first machines and each of the second plurality of types of second machines, respectively. The first processing device is configured to compare a first profile of a first machine of a first type to be transferred to a second profile of a second machine of a second type to which the host image is to be transferred. The first processing device is further configured to conform at least one property of a host image of the first machine to at least one corresponding property of the second machine based, at least in part on the comparison, and to cause transfer of the conformed host image to the second machine, via a network. The second processing device is configured to configure the second machine with at least one conformed property of the host image. 
     In accordance with another embodiment of the invention, a disaster recovery system is disclosed comprising a recovery manager comprising a processing device, such as a central processing unit or microprocessor, for example, a backup storage device to backup a client system, and recovery machines, each coupled to a network. The recovery manager stores profiles of representative client and recovery machines. The processing device compares the profiles of the client machine and a recovery machine to which the client machine will be recovered to, and conforms at least certain properties of a host image from the client machines to a respective recovery machine based, at least in part on the comparison. The processing device also injects a program into respective host images that runs during boot up on a respective recovery machine, to configure the recovery machine with the conformed properties of the host image. Configuration can take place during a limited, safe mode boot up of the recovery machine, which may be followed by a normal mode boot up. A second limited boot may be required prior to the first limited boot up to effectuate certain configuration changes, such as changing the hardware abstraction layer (“HAL”) of the recovery machine to the HAL of the client machine and host image. To conform the host image to properties of the recovery machine, network storage drivers, storage adapter drivers, and/or the partition style, of the host image may be conformed to that of the recovery machine, for example. 
     In accordance with another embodiment of the invention, a transfer manager is provided in a first system comprising first machines, to transfer host images of first machines to second machines across a network, in a similar manner as described above with respect to recovery to a disaster recovery system. In accordance with another example of an embodiment of the invention, failback to client machines or local recovery machines at a client system is conducted by a recovery manager in a disaster recovery system or in a client system, in a similar manner as described above with respect to recovery to the disaster recovery system. In accordance with another example of an embodiment of the invention, migration of a host image from a first client machine to a second client machine is similar to the recovery of a host image from a client machine to a recovery machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of an example of a disaster recovery environment including a disaster recovery system and a client system protected by the disaster recovery system, in accordance with an embodiment of the invention; 
         FIG.  2    is a block diagram of an example of a recovery manager, in the embodiment of  FIG.  1   ; 
         FIG.  3    is a block diagram of an example of a recovery machine, in the embodiment of  FIG.  1   . 
         FIG.  4    is a block diagram of an example of a client machine, in the embodiment of  FIG.  1   ; 
         FIG.  5    is a flowchart of an example of a method of recovering a host image of a client machine to a recovery machine during disaster recovery, in accordance with an embodiment of the invention. 
         FIG.  6    is a flowchart of an example of a method of creating a machine hardware profile of a client machine or a recovery machine, in accordance with an embodiment of the invention; 
         FIG.  7    is a flowchart of an example of a method of image conversion, in accordance with an embodiment of the invention; 
         FIG.  8    is a flowchart of an example of a method of injecting of drivers, shown in the method of  FIG.  6   ; 
         FIG.  9    is a flowchart of an example of a method of booting a recovery machine with the conformed host image of a client machine; 
         FIG.  10    is another example of a disaster recovery environment in accordance with an embodiment of the invention; and 
         FIG.  11    is a block diagram of an example of a data migration environment, in accordance with another embodiment of the invention. 
     
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT 
     Methods and systems for transferring a host image of a first machine to a second machine, such as during disaster recovery or data migration, are disclosed. In one example, a first profile of a first machine of a first type, such as a first client machine, is compared to a second profile of a second machine, such as a recovery machine or a second client machine of a second type different from the first type, to which the host image is to be transferred, by a first processing device. The first and second profiles each comprise at least one property of the first type of first machine and the second type of second machine, respectively. At least one property of a host image of the first machine is conformed to at least one corresponding property of the second machine. The conformed host image is provided to the second machine, via a network. The second machine is configured with at least one conformed property of the host image by a second processing device of the second machine. 
     In accordance with embodiments of the invention, systems and methods are provided for the automatic, bare metal recovery of physical-to-physical (“P2P”), virtual-to-virtual (“V2V”), virtual-to-physical (“V2P”), and physical-to-virtual (“P2V”), first machines to second machines, respectively, where the type of the second machine and the type of the first machine may be different and may not be known to each other or to respective client and recovery systems. As used herein, the term “type” means type of hardware and/or type of manufacturer. The type of hardware may include servers, desktop computers, laptop computers, and/or work stations, while the type of manufacture may include Dell, Inc., Round Rock, Tex. (“Dell”), Hewlett Packard Company, Palo Alto, Calif. (“HP”), Lenovo, Morrisville, N.C. (“Lenovo”), etc. 
     For example, a Dell client server suffering a shutdown due to a power failure may be recovered to an HP recovery server, and the HP recovery server may be failed back to the same or another Dell server when the server or the client system becomes operational again. In another example, a plurality of Lenovo laptops may be recovered to a virtual machine running within a hypervisor on a Dell server, and may be failed back to Lenovo or other laptops. Transfer to a different type of machine than the client machine, where the type of first machine and the type of second machine is not predetermined, is enabled in accordance with embodiments of the invention by comparing profiles of each machine and modifying a backed up copy of the first machine, referred to as a host image, and/or the second machine, so that a host image of a first machine can run on the second machine. 
       FIG.  1    is a block diagram of an example of a disaster recovery environment  10  including a disaster recovery system  12  and a client system  14  protected by the disaster recovery system, in accordance with an embodiment of the invention. The disaster recovery system  12  comprises a remote recovery manager  16 , one or more remote recovery devices or machines  18   a,    18   b  . . .  18   n,  and a remote backup device  20 , each of which are coupled to a network  22 . The client system  14  in this example comprises one or more client machines  24   a,    24   b  . . .  24   n  and a local backup storage device  26 , each of which is coupled to the network  22 . One or more local recovery machines (not shown) may also be coupled to the network as well, for local recovery of the client system. Local recovery is discussed further below. 
     The network  22  may comprise any one or several different types of networks. Communications over the network may take place by means of IP protocols or fibre channel protocols, for example. The network may be an intranet, the Internet, a wide area network (“WAN”), a local area network (“LAN”), such as an Ethernet, a fibre channel storage area network (“SAN”), or an Internet small computer systems interface (“iSCSI”), for example. 
     The remote recovery manager  16  comprises one or more processing devices  28 , such as a central processing unit or microprocessor, for example. The remote recovery manager  16  also includes at least one hard drive  30 . Other memory  31 , such as ROM and/or RAM, may also be provided. The recovery manager may be a server or computer, for example. The remote recovery manager  16  may alternatively be in other locations of the system, such as part of the remote backup storage device  20 , in which case, the processing device  42  on the remote backup storage device may be configured to perform the functions of the recovery manager. The recovery manager  16  is configured to implement aspects of embodiments of the present invention under the control of a software engine  30   a  on the hard drive  30  or in other storage run by the processing device  28 , for example. The recovery manager  16  may also be configured in whole or in part to implement aspects of embodiments of the invention by hardware, such as an ASIC, or by a combination of hardware and software. 
     The remote backup storage device  20  periodically backs up the local backup storage device  26  in manners known in the art, such as by using replication and a snapshot marker, for example. An example of replication is described in U.S. Pat. No. 7,155,585, which is assigned to the assignee of the present invention and is incorporated by reference herein. An example of the use of a snapshot marker is described in U.S. Pat. No. 7,165,145, for example, which is also assigned to the assignee of the present invention and is incorporated by reference herein. IPStor(R), available from FalconStor, Inc., Melville N.Y., which incorporates aspects of U.S. Pat. Nos. 7,165,145 and 7,155,585, may be used, for example. Data deduplication may be performed, as well, as described in U.S. Patent Publication No. US 2012/0089578 A1, for example, which was filed on Aug. 21, 2011, is assigned to the assignee of the present invention and is incorporated by reference herein, for example. 
     Returning to  FIG.  1   , the remote backup storage device  20  may comprise one or more servers or computers, each comprising a processing device  32 , such as a central processing unit or microprocessor, and at least one storage device  34  that may define a database DB, for example, as shown in  FIG.  1   . Other memory is typically provided as well, such as ROM and/or RAM (not shown). The remote backup storage device  20  may provide physical and/or virtual memory storage. Backup from the local backup device  20  to the remote backup device may take place periodically or continuously, depending on the desires of the client system  14  and the capabilities of the remote backup storage device  20 , for example. 
     For each client machine  24   a,    24   b  . . .  24   n  in the client system  14 , there is typically a corresponding respective remote recovery machine  18   a,    18   b  . . .  18   n  in the disaster recovery system  12 , although that is not required. The remote recovery machines  18   a,    18   b  . . .  18   n  may comprise remote physical or virtual machines, computers, laptop computers and/or work stations, for example. A hypervisor server may run on multiple virtual recovery machines for multiple client machines. Remote virtual machines may be created as needed for disaster recovery, and removed when no longer needed, so that the disaster recovery system  12  does not have to pre-allocate or create them ahead of time. 
     The remote recovery machines  18   a,    18   b  . . .  18   n  each comprise a processing unit  42 , such as a central processing unit or microprocessor, for example, a hard drive  44 , and additional memory  46 , such as ROM and/or RAM, as shown in  FIG.  3   . The remote recovery machines may be virtual machines defined on a server, for example, as discussed above. In accordance with embodiments of the invention, the remote recovery machines may or may not be the same type of hardware as the respective client machine, may be from a different manufacturer, and are not preconfigured to receive a host image from a specific client machine or type of client machine. 
     Returning to  FIG.  1   , the client machines  24   a,    24   b  . . .  24   n  in the client system  14  each comprise a processing device  50 , such as a central processing unit or microprocessor, for example, a hard drive  54 , and memory, such as ROM and/or RAM, as shown in  FIG.  4   . The client system  14  may comprise physical and/or virtual client machines  24   a,    24   b  . . .  24   n,  such as physical and/or virtual servers, desktop computers, laptop computers and/or workstations, for example. 
     Client machines  24   a,    24   b  . . .  24   n  are regularly backed up to the local backup storage device  26 , in manners known in the art, such as by replication and use of a snapshot marker, for example, as discussed above. IPStor(R) may be used, for example, and data deduplication may also be provided, as is also discussed above. The local backup storage device  26  comprises a processing device  60 , such as a central processing unit or microprocessor, one or more hard drives  62 , and a storage device  64 , which may be a database (“DB”), for example. In particular, the backup storage device  26  backs up copies of the hard drives of the client machines  24   a,    24   b  . . .  24   n,  referred to as host images, as described above, in the database  64 , for example, via the network  22 . The storage device  64  may provide physical and/or virtual memory storage. The local backup storage device  26  provides backed up host images to the remote backup storage device  20  via the network  22  periodically or continuously during backup procedures defined by the client system  14 , depending on the desires of the client system  14  and the capabilities of the remote backup storage device  20 , for example, as discussed above. 
     To describe a server or desktop computer protected in accordance with embodiments of the invention, the type of machine, including the manufacturer of the machine (Dell, HP, Lenovo, etc.), the hardware (desktop, laptop, server, etc.), and the host image need to be described. For example, an IBM System x3650 server running Windows® 2008 with applications such as SQL Server 2008 would be identified as an “IBM System x3560” machine running a host image including Windows® 2008, the applications, and the data. 
     Client and recovery machines of different types and in different locations may have different network settings and addresses. Client and recovery machines of different types may also have different drivers, such as different storage drivers, different interface card drivers, and different system drivers, such as different USB drivers and power controllers, for example. Client and recovery machines of different types may also have different adapters, such as storage adapters, IDE adapters, network adapters, display adapters, host bus adapters (“HBA”) and/or video adapters, for example. They may also have different hardware abstraction layers (“HAL”) and/or SAN architectures. These differences may prevent the host image from a client machine of one type from running on the recovery machine of another type, or prevent the recovery machine from performing all the desired functions of the respective client machine. 
     In order to recover a respective client machine, such as the client machine  24   b,  to a remote recovery machine, such as remote recovery machine  18   b,  which is different from client machine  24   b,  in accordance with embodiments of the invention, the host image of the client machine  24   b  is configured to run on the remote recovery machine  24   b.  For example, if the adapters on a respective client machine are different than those on the recovery machine to which the host image is to be recovered, then compatible drivers need to be provided on the host image in order for the host image to boot and operate on the recovery machine. Certain conversions are performed on the respective host image and other conversions are performed on the recovery machine, upon boot up. In order for the host image to be converted, it must be a writeable host image. For example, network settings for the recovery machine, which are provided to the host image, are loaded on the recovery machine during boot up. If the host images stored on the local or remote backup storage devices  26 ,  32  are not writeable, then a writeable copy of the host images is prepared for conversion. 
     The properties of the client machines  24   a,    24   b  . . .  24   n  and recovery machines  18   a,    18   b  . . .  18   n  may be stored by the remote recovery manager  16  and compared during the recovery process, to determine the changes that are necessary to the host image to enable it to run the recovery machine. The respective characteristics may be stored in respective profiles, each referred to as a machine hardware profile (“MHP”), which is stored by the recovery manager and listed in a directory of the hard drive  30 , for example. 
       FIG.  5    is an example of a flowchart of a method  100  of recovering a host image of a client machine to a recovery machine during disaster recovery, in accordance with an embodiment of the invention. Profile information for representative client machines and recovery machines is collected, in Step  102 , prior to a disaster taking place. The profiles may be stored in the remote recovery manager  16 , for example. When recovery is required, the profiles for a client machine of a first type to a recovery machine of a second, different type, are compared, in Step  104 . Properties of a host image of the client machine are conformed to the properties of the recovery machine based on the comparison, in Step  106 . 
     The conformed host image is provided to the recovery machine, in Step  108 . The recovery machine is then configured based on the conformed properties of the host image during a first, limited boot up, such as a safe mode boot up, in Step  110 . The recovery machine is then rebooted in a second boot up, in normal mode. After the normal mode boot up, the recovery machine may operate as if it were the client machine. 
     An MHP is generated for at least every OS/hardware combination of the client machines  24   a,    24   b  . . .  24   n  in the client system  14  and every OS/hardware combination of the remote recovery machines  18   a,    18   b  . . .  18   n  in the disaster recovery site  12 . For example, if a client has  200  client machines of two different hardware types (Dell and Lenovo, for example), each of which run one of two different operating systems, it would be necessary to run the MHP on four representative client machines, each having a different combination of hardware and OS. The same applies to the remote recovery machines  18   a,    18   b  . . .  18   n.    
     Prior to the recovery, the recovery machines  18   a,    18   b  . . .  18   n  do not have an operating system. In order for the host image to run on the recovery machine, the operating system on the host image, which is the operating system of the client machine  24   b,  must be able to launch on the recovery machine  18   b.  The storage drivers on a host image must therefore be the proper drivers for the respective recovery machine on which the host image will be recovered, in this example recovery machine  18   b.  For example, if the hard drive  44  on the remote recovery machine  24   b  is an integrated disk electronics (“IDE”) disk, the host image machine needs an IDE driver. If the hard drive  44  is a small computer system interface (“SCSI”) disk from a particular manufacturer, the host image needs the SCSI drivers from that manufacturer. The storage drivers required for respective recovery machines are identified in the MHP. 
     In order for the remote recovery machine to communicate with the network  22  and seamlessly take the place of the client machine  24   b  in functionality (to receive data directed to the client machine  24   b,  for example), the network settings of the host image, based on the client machine  24   b,  need to be conformed to that of the recovery system  12 . The name of the client machine  24   b,  however, is preserved so that data being sent to the client machine  24   b  will be received by the recovery machine  18   b.  If the IP address is changed, it will typically be mapped to the recovery machine  24   b  by a domain name system (“DNS”) server at the recovery site  12 . The IP address may need to be changed in order to successfully recover to the disaster recovery system  12 , unless the disaster recovery system  12  uses the same IP address subnet as the client system  14 . 
     It would be advantageous to conform other drivers, adapters, and settings of the host image to that of the recovery machine, as well, for further functionality of the host image on the recovery machine, such as video adapters, which could provide higher screen resolution, and power control drivers, which can provide remote power control capability, such as intelligent platform management interface (“IPMI”), integrated lights out (“iLO”) and/or lights out management (“LOM”), for example. 
     In one embodiment of the invention, to conform the host image, at least in part, to the environment of the recovery machine  18   b,  so that the host image can run on the recovery machine, the remote recovery manager  16  compares the MHPs of respective client and recovery machines, mounts the backup storage device storing the host image (either the remote backup storage device or the local backup storage device), and replaces the storage drivers on the host image by the storage drivers on the recovery machine, if necessary, via a software conversion engine  30   a,  referred to as RT Convert, which is stored on the hard drive  30  of the remote recovery machine and run by the processing device  28  of the recovery manager  16 . The storage drivers of the recovery machine may be stored in the MHP for the respective recovery machine, for example, and retrieved if necessary. Additional information required for the operation of the host image on the recovery machine may be provided in a job file. Such information may include configurable information, such as network settings, service settings, geometry settings, and conversion policies, for example. Similarly, RT Convert  30   a  changes the network settings of the host image based on network settings of the remote recovery machine  24   b  found in the MHP for the recovery machine, or in the job file. Other characteristics of the host images may be changed, as well, based on the comparison of the respective MHPs. 
     The MHPs may be collected by a software utility. In one example, the MHPs for the client machines  24   a,    24   b  . . .  24   n  are collected by the client system  14 , which runs the utilities prior to a disaster taking place. The MHP software utility may be downloaded to the client system  14  by the disaster recovery site  12 , via the network  22 , across the network. The client system may install the MHP software utility on the hard drive  62  of the local backup storage device  26 , or the utility may be placed there by the remote recovery manager  16  via a network share across the network  22 , for example. The MHP software utility may also be a part of the backup software run by the local backup storage device  26 . The processing device  60  of the local backup storage device  26  may run the MHP utility on all or certain of the client machines  24   a,    24   b  . . .  24   n,  via a network share, for example. The profiles generated by the MHP utilities may be collected by the local storage device  26 , stored on the local backup storage device  16 , on the hard drive  62 , the storage device  64 , or other storage (not shown), and may then be sent to the remote recovery manager  16  across the network  22 , via a network share or SAN, for example. 
     The MHP utility may also be run by the remote recovery manager  16  on the client machines, via a network share with the client machines. The utility may be run by a respective processing device when a recovery job is first set up, and then whenever a new hardware/OS combination is introduced to the client system  14  or data recovery system  12 , for example. It may also be run on the host images of the client machines  24   a,    24   b  . . .  24   n  whenever host images are backed up, for example. 
     The recovery manager  16  may store the respective MHPs in an MHP directory, with an identification of the respective client machine type, on the hard drive  30 , for example. In one example, each MHP is stored in a different sub-directory of the MHP directory. 
     Since the recovery machines  18   a,    18   b  . . .  18   n  are off and do not include an operating system, in order to collect MHPs for the remote recovery machines  18   a,    18   b  . . .  18   n  that are of different hardware/OS configuration than any profiles for the recovery machines that have already been collected, the recovery machines must be booted up with the same OS as the respective client machine to be recovered to it. This may be done manually by an operator at the recovery site  12  or by the remote recovery manager  16 , which may boot up the remote recovery machines  18   a,    18   b  . . .  18   n,  provide a temporary operating system of the same type as the respective client machine to be recovered, and then run the MHP utility on some or all of the remote recovery machines, as needed. As above, in one example, the MHPs of the remote recovery machines  18   a,    18   b  . . .  18   n  are stored in a directory of the remote recovery manager  16 , which then removes the operating system and shuts down the recovery machines. The MHPs of the recovery machines  18   a,    18   b  . . .  18   n  may be stored in the same directory storing the MHPs of the client machines  24   a,    24   b  . . .  24   n,  a related directory, or a different directory, for example. 
     The MHP utilities collect the hardware device identification (Dell, Lenovo, etc.), the OS type, the driver information, the adapter information, and HAL information, for the client machine and the recovery machines by examining the appropriate directories on the respective machines. For example, the driver information is typically included in a Windows® system driver directory, such as C:\Windows\System32\drivers, for example. The actual drivers and adapters may be included in the MHPs, as well. 
     In one example, the collected MHPs are placed into one or more XML files, for example, by the processing device  60  under the control of the MHP utility, in the local backup storage device  26 . The XML file and the drivers may be placed into a cabinet (“CAB”) file, for example, by the utility, for ease of transport to the remote recovery manager  16  across the network  22 . The CAB file may contain several XML files and drivers for multiple OS/hardware combinations. A plurality of MHPs for individual OS/hardware combinations may be combined to form a larger profile to define the specification for many OSs on one hardware model. The CAB file or files for the client system  14  are provided to the remote recovery manager  16  by the local backup storage device, via a network share, or they may appear on the remote recovery manager as a virtual file via a SAN, for example. The remote recovery manager  16  removes the XML file or files and the drivers from the CAB file, and stores them in respective sub-directories, as described above, for example. 
     The processing device  28  of the recovery manager  16 , under the control of the MHP utility or manually, may similarly create the XML files and place the XML files and drivers into the directory. The directory or sub-directories of the MHPs for the client system  14  and the disaster recovery system  12  may be shared so that MHPs are centralized and the host images for many client machines may be converted by the same or multiple conversion engines or one or more recovery managers  16 . 
       FIG.  6    is a flowchart of an example of a method  300  of creating an MHP for the client machines  24   a,    24   b  . . .  24   n  and/or recovery machines  18   a,    18   b  . . .  18   n,  as needed, in accordance with an embodiment of the invention, by a respective processing device under the control of a utility. The utility may be run by the processing device  60  of the local backup device  26 , the processing devices  50  of the respective client machines, or the processing device  28  of the remote recovery manager  16 , in accordance with one embodiment of the invention, to create MHPs for client machines  24   a,    24   b  . . .  24   n.  The utility may be run by the processing device  28  of the remote recovery manager, a processing device  42  of a respective recovery machine, or the processing device  32  of the remote backup device  20 , to create MHPs for respective recovery machines and recovery machines  18   a,    18   b  . . .  18   u.    
     The utility starts to collect hardware information concerning a client machine, in Step  302 . Drivers, hardware, model, OS, and HAL type are enumerated from the operating system of the respective client machine, in Step  304 . All drivers for the devices in the XML are selected, in Step  306 . A file name and location are selected for a CAB file that will contain the respective XML file or files, in Step  308 . An XML file including the hardware profile information is created, in Step  310 . The CAB file including the XML file and the driver files is created, in Step  312 . The utility ends, in Step  314 . The CAB file is placed in the network share of the local backup storage device  26 , for example, and imported by the remote recovery manager  26  from the network share or SAN. The utility run by the processing device  28  of the remote recovery manager  16  to create profiles for the recovery machines operates in a similar manner, except that it is not necessary to create CAB files, although that is an option. As noted above, the utility may be run on all client machines and recovery machines, or only representative machines. 
     A recovery procedure starts when the disaster recovery site is informed by the client system  14  to run a predetermined job, which may be a run in a test mode or an actual disaster recovery mode, for example. The parameters of a job may be defined in a job file by the client system  14  so that the job file will be available to run the test or recovery prior to the event. In one example, the job file is an XML file, which is stored by the remote recovery manager  16  in a job directory. The job file may define the particular settings to be changed on the host image in order for the host image to operate on the respective recovery machines  18   a,    18   b  . . .  18   c  that the respective client machines  24   a,    24   b  . . .  24   c  are to be recovered to, such as the network settings to be enabled and disabled, power control management, whether a particular machine is an active directory (“AD”) server, and/or the AD recovery policy, for example. The job file may include the network settings, such as the IP address, network mask, gateway address, DNS address, and/or Windows® Internet Name Service (“WINS”) address for recovery machine. The network settings may be in the MHP of the respective recovery machines, instead or in addition to being in the job file. 
     In an actual disaster, the client system  14  instructs the disaster recovery system  12  to run a disaster recovery job to recover all or some of the client machines  24   a,    24   b  . . .  24   n.  The client system  15  may inform the disaster recovery system  12  that recovery of the local backup storage device  26  is required, as well. The disaster recovery site  12  may also automatically monitor the client machines  24   a,    24   b  . . .  24   n  or the client system  14  via a heartbeat, or other methods, for example. A path to the directory containing the MHPs is then provided to an RT Convert conversion engine  30   a  run by the processing device  28  of the remote recovery manager  16 , which accesses the appropriate job file and the MHPs in the respective sub-directories. 
     In one example the remote recovery manager  16  mounts a network share of the remote backup storage device  20  via the network  22 , and runs the RT Convert conversion engine  70  on the current host images backed up to the remote backup device. If the remote backup storage device  20  is a SAN storage device, the host image may be presented to the remote recovery manager  16  as one or a plurality of virtual disks, which are mounted by the recovery manager  16 . The remote recovery manager  16  may instead be configured to mount the local backup storage device  26  across the network  22 , if it is still functioning. The local backup storage device  26  may have more current host images than the remote backup storage appliance, depending on how frequently the host images are backed up from the local backup storage device to the remote backup storage device, and when in relation to the last backup the disaster took place. Alternatively, if the local backup storage device  26  is still functioning, it may provide the most current host images to the remote backup storage device  20 , upon the request of the remote recovery manager  16  or the remote backup storage device, for use by the remote recovery manager. 
     To conform each host image for each client machine  24   a,    24   b  . . .  24   n  that needs to be recovered to a respective recovery machine  18   a,    18   b  . . .  18   n,  the RT Convert engine  30   a  performs one or more of the following operations on each host image to be recovered in accordance with embodiments of the present invention: configure Windows® services start up settings; inject the network configuration; preload storage adapter drivers for OS boot up on the respective recovery machine; prepare the drivers for boot up on the respective recovery machine; fix the geometry of boot disk, which contains the operating system on the host image, if necessary; change the partition style, if necessary; enable authoritative (“AD”) or non-authoritative recovery; determine whether the HAL of the recovery machine needs to be changed; and enable safe mode boot up on the respective recovery machines, for example. The changes may be made directly to the host image, or a separate host image may be created including the changes with respect to the original host image. In that case, both the original host image and the changed host image would be provided to the respective recovery machine. The changes are based on a comparison of the MHPs for the client machine and respective recovery machine, or MHPs of representative client machines and recovery machines, as well as the information in the job file. 
     RT Convert also injects into the host image a program that will run on the respective recovery machines during boot up of the recovery machines  18   a,    18   b  . . .  18   n,  to complete the recovery process. This program, referred to as RT Rehome, performs the remaining conversions that must be done to the recovery machines  18   a,    18   b  . . .  18   n  during boot up in order for the respective host image to run on them, and then reboots the recovery machine in a normal mode. 
     After the RT Convert process is completed, each host image is assigned to a respective recovery machine  18   a,    18   b  . . .  18   n  and transferred to the respective recovery machine by the remote recovery manager  16 , via a network share or SAN of each recovery machine, for example, for boot up. The host image may appear on the respective recovery machine as a virtual disk, such as a SAN disk. 
     The RT Rehome program injected into the host image by RT Convert is run by the processing device  42  of each recovery machine  18   a,    18   b  . . .  18   n  receiving a host image virtual disk. The conversion operations that need to be done on the respective recovery machine  18   a,    18   b  . . .  18   n  when the host image is booted on the respective remote recovery machine to recover the host image, are controlled by RT Rehome, in this example. RT Rehome runs on the first boot of each remote recovery machine  18   a,    18   b  . . .  18   n  by the processing device  42  of each recovery machine. The first boot of the remote recovery machine will be a limited boot, such as a safe mode boot, which only boots the operating system. Two limited boot ups may be required. 
     RT Rehome performs one or more of the following operations in accordance with embodiments of the present invention during the safe mode boot: installs drivers, installs adapters, configures network settings (IP address and network mask, gateway address, DNS address, and/or Windows® Internet Name Service (“WINS”) address), add Windows® services, adds registry keys, configures clusters, configures SCSI, ensures that volume mount points and driver letters are assigned as they were on the client machine, updates HAL, if necessary, configures programs on the host image, such as SAN Disk Manager (“SDM”) and/or Intelligent Management Agent (“IMA”), available from FalconStor, Inc., Melville, N.Y., to work in new environment by unregistering the IMA from the local backup storage device  26  and registering it to the remote backup storage device  20  (and vice-a versa during failback). In addition, it may disable FalconStor DiskSafe, if it is on the host image, for recovery, to ensure that it does not try to backup over a WAN during recovery, which would slow down the recovery machine. After this is completed, the respective recovery machine is shut down by the RT Rehome and then boots into normal mode. The client machine will then be recovered to a respective recovery machine. If HAL update is required, that may be performed in a first limited boot up, such as a Windows(R) mini set up, which can then be followed by the second, limited, safe mode boot up, and then the normal boot up. 
       FIG.  7    is a flowchart of an example of a method  400  of image conversion by the processing device  28  of the recovery manager  16  under the control of RT Convert, for example, in accordance with an embodiment of the invention. After being informed by a client system  14 , that recovery is required, image conversion starts in Step  402 . In this example, the host image path to the local backup storage device  26  is loaded to the RT Convert engine  30   a,  in Step  404 . The image path defines the location of the host image for a respective client machine on the local backup server  26 , for example. If the local backup device  26  is a SAN device, then the path to the location of the host image on the SAN device is defined. If the local backup device  26  is not a SAN device, the path may be to a network share of the backup storage device, which may be mounted by the recovery manager  16  to run RT Convert on the backup storage device  20 , for example. 
     The MHP XML files are retrieved by the processing device  28  of the recovery manager  16  from the directory and loaded to the RT Convert engine  30   a,  in Step  406 , by the processing device  28  of the remote recovery manager  16 . 
     The job files are loaded to the RT Convert engine by the processing device  28 , in Step  406 . The job file in this example contains operating system (“OS”) related information, such as a disk number assigned to the OS disk of the host image, service settings, geometry settings (such as the location of the start of boot), conversion policies, network settings (including network addresses), power control management, AD recovery policy, and/or hardware IDs, for example. 
     It is then determined whether a Windows® folder including the driver information (such as folder  32 , for example, described above) is found in the host image, in Step  410 . If not, then image conversion is ended, in Step  412 , because the method of this embodiment of the invention cannot proceed without the driver information. 
     If Yes, then the RT Convert engine  30   a  looks at the partition style, in Step  414 , to determine whether the partition of the host image is a globally unique identifier (“GUID”) partition table (“GPT”) (Step  416 ), used when disks have more than 2 terabytes of data, or a master boot record (“MBR”), used when disks have less than 2 terabytes of data. 
     If the partition style of the host image is GPT, then it is determined whether it is necessary to convert the partition style to MBR because the respective recovery machine does not support GPT, in Step  418 , based on the partition style of the respective recovery machine identified in the respective MHP. 
     If it is necessary to convert to MBR, it is then determined whether conversion is possible, in Step  420 . If not, because the OS disk of the host image is greater than 2 terabytes, then image conversion ends, in Step  412 , because the recovery machine cannot support GPT boot. 
     If it is necessary to convert to MBR, and it is determined that conversion is possible in Step  420 , then the partition is converted, in Step  422 . 
     It is then determined whether all the needed device drivers can be found in the MHP of the recovery machine, in Step  424 , by comparing the drivers identified in the MHP of a respective recovery machine to the actual drivers in the MHP of that recovery machine. The drivers may include the storage drivers for the boot disk, SCSI controllers, network drivers, video drivers, and/or power control drivers, for example. The drivers are identified by hardware IDs in the MHPs. If all the drivers cannot be found, in this example, image conversion ends, in Step  412 . 
     If the partition style is not GPT (Step  416 ) or conversion to MBR is not needed (Step  418 ), the method also proceeds to Step  424  to find all the device drivers. If all the file drivers cannot be found in Step  424 , image conversion is ended, in Step  412 , because recovery to a recovery machine cannot be provided without all the file drivers. 
     If all the file drivers can be found in Step  424 , safe mode boot up is enabled on the host image by a setting on the OS disk of the host image, in Step  426 , so that the first boot up on the recovery machine will be a safe mode boot up. 
     It is then determined whether the respective machine is an active directory (“AD”) server, in Step  428 . The active directory server keeps track of users, Exchange servers, computers, and other objects, and includes their security access control information. If the server is an AD server, then the AD recovery policy, which is also in the job file, is applied, in Step  430 . The AD recovery policy may include whether the server is an authoritative server, to which an authoritative recovery is to be applied, or not. In an authoritative recovery, the AD server is a master and will synchronize other AD servers, while in a non-authoritative recovery, AD server is a slave and will by synchronized with respect to another AD server. 
     Mounted device volume information is gathered from an image registry on the host image and recorded in a separate file on the host image for use by RT Rehome, in Step  432 . The device volume information includes volume drive letters and mount points on the image, for example, to ensure that all volumes are mounted correctly when the host image boots on the respective recovery machine. If the host image is not for an AD server (Step  428 ), the process proceeds to Step  432 , as well. 
     Conversion reboot settings are applied, in Step  434 , so that the recovery machine boots in safe mode. Service control settings are applied, in Step  436 , to allow the conversion process to enable and disable services that may hinder recovery speed and recovery boot. Service control settings may include hardware OEM/vendor specific services that were enabled on the client machine, such as fingerprint identification, RAID software, hardware monitoring or other software related services, such as antivirus, backup software, etc. 
     The drivers needed to run on the recovery machine are loaded into the host image, in Step  438 , from the MHP of the recovery machine. The drivers may be placed in a directory, such as the Windows® System driver directory, for example. 
     It is then preliminarily determined whether it is necessary to change the HAL, in Step  440 , by comparing the HAL in the MHP of the client machine and the MHP of the respective recovery machine, to ensure that the recovery machine has the HAL required to run the host image. If not, the HAL has to be replaced on the host image so that it can be downloaded to the recovery machine. 
     If HAL replacement is required, it is determined whether the operating system is Windows® 2003 or older version, in Step  444 . If not, then the OS version is Windows® 2008 or later, so a detect HAL option on boot configuration data (“BCD”) configuration is enabled to change the HAL, during safe mode reboot, in Step  446 . If the operating system is Windows® 2003 or older, then it is determined whether the central processing unit is a 32 bit processor, in Step  448 . If it is a 32 bit processor, then a limited boot up process, referred to as “Windows® mini setup,” is enabled in RT Rehome to change the HAL, in Step  450 . A separate boot up is provided for HAL replacement in this example because HAL replacement can be complex, but that is not required. Windows® mini set up may be enabled by modifying the Windows® registry and preparing a Windows® answer file on the host image. RT Convert then configures the first boot on the recovery machine to change the HAL. In this case, the first boot up of the recovery machine is the mini-setup boot up, which will be followed by the safe mode reboot and then a normal reboot. 
     If the central processing unit of the recovery machine is not a 32 bit processor, then it is a 64 bit processor, and HAL replacement is not required because the HALs are compatible. RT Convert proceeds to copying the network configuration and RT Rehome into the host image, in Step  452 . The method proceeds to Step  452  after Steps  446  and  448 , as well. 
     An RT Convert agent service is added, in Step  454 , to run RT Rehome on the first boot of the recovery machine. 
     If the boot disk geometry of the client machine is different than the boot disk geometry of the respective recovery machine, which are both defined in the job file, the boot disk geometry on the host image is modified to conform to that of the recovery machine, in Step  456 . 
     Image conversion is ended, in Step  412 . 
       FIG.  8    is a flowchart of an example of a method  500  of injecting drivers, shown in Step  438  of the method  400  of  FIG.  6   . Driver injection starts in Step  502 . Information (“INF”) files are scanned on the OS disk of the host image to find INF files that match the INF files in the MHP for the recovery machine, in Step  504 . If a match is not found, then the RT Convert process ends, as indicated in Steps  424  and  412  of  FIG.  7   , as discussed above. 
     It is then determined whether the driver of the recovery machine is a SCSI or IDE adapter driver, in Step  506 . If not, the driver package for the INF adapter driver is copied into the OS folder of the recovery machine, and RT Rhome is configured to install the INF adapter driver during safe mode reboot, in Step  508 . Driver injection then ends in Step  510 . 
     If the driver is an SCSI or IDE adapter driver (Step  506 ), then it is determined whether the driver is already installed on the host image, in Step  512 . If yes, then the process moves to Step  508 , discussed above, to update the driver version, if necessary. 
     If not, then the INF syntax is followed to copy the driver files, add registry keys, add services, and install drivers on the host image, in Step  514 . In addition, RT Rehome is configured to continue conversion. The process then ends in Step  510 . 
       FIG.  9    is a flowchart of an example of the RT Rehome process  600 , which is run by the processing unit  42  of the respective recovery machine during the first boot up of the recovery machine, as discussed above. OS boot up starts in Step  602 . The boot up mode is determined, in Step  604 . If mini set up was enabled during the RT Convert process in Step  450 , then the operating system on the host image is first booted in the Windows(R) mini set up mode, to replace the HAL based on an answer file, in this example, as discussed above. 
     When mini set up is complete, in Step  606 , safe mode is then enabled and safe mode reboot is conducted, in Step  608 , to complete other conversions on the recovery machine, in safe mode, in Steps  610 - 614 . RT Rehome checks the host image to determine whether new device drivers are present and if so, device set up of the OS is called to install the device drivers, in Step  608 . If mini set-up is not required in Step  604 , then the process also proceeds directly to Step  610 . 
     After device setup to update device drivers, in Step  610 , network settings, including network addresses, are applied, in Step  612 , from the host image, for example. It is then ensured that disk volume configuration on the recovery machine is the same as the original disk volume configuration of the client machine, which is on the host image, in Step  614 , by ensuring that all driver letters and mount points are set to the same settings as in the respective client machine, so that applications will run as if on the client machine. 
     Safe mode boot up is then disabled, in Step  616 , to allow the recovery machine to reboot the host image in normal mode, in Step  618 . During the normal mode boot up, the operating system, data, and applications that were stored on the hard drive of the respective client machine are loaded to and will run on the recovery machine, so that it will operate as did the respective client machine. 
     If mini set up was performed, then the boot up process of the recovery machine includes three boot ups, the mini set up boot up, the safe mode boot up, and the normal mode boot up. If mini set up is not performed, then there are two boot ups, the safe mode boot up and the normal mode boot up. 
       FIG.  10    is another example of a system  700  that may be used in accordance with embodiments of the invention. Components found in  FIG.  1    are similarly numbered. In this case, in the disaster recovery site  702 , the remote recovery manager  16 , the remote recovery machines  18   a,    18   b  . . .  18   n,  and the remote backup storage device  20  are coupled to a first SAN  703 . 
     In the client system  704 , the client machines  24   a,    24   b  . . .  24   n  and the local backup storage device  26  are coupled to a second SAN  705 . The client machines backup host images to the local backup storage device  26 , as described above. In this example, local recovery machines  706   a,    706   b  . . .  706   n  are provided, coupled to the SAN  705 . The local recovery machines may have the same structure as the remote recovery machines  18   a,    18   b  . . .  18   c  of  FIGS.  1  and  3   . A local recovery manager  708  is also coupled to the second SAN  705 . The local recovery manager  708  may have the same structure as the remote recovery manager  16 , of  FIGS.  1  and  2   . 
     The disaster recovery site  702  is coupled to the client system  704  through a network  714 , which may be a WAN, for example. In particular, the remote recovery manager  16 , the remote backup storage device  20 , the local backup storage device  26 , and the local recovery manager  708  are also coupled to a network  714 . The local backup storage device backs up host images from the client machines to the remote backup storage device across the network  714 , in manners known in the art, such as by using replication and snapshot markers, for example, as described above. IPStor(R) may be used, for example, and data deduplication may be provided, as is also described above. 
     In this example, recovery to the recovery machines  18   a,    18   b  . . .  18   c  of the disaster recovery site  702  may take place in the same manner as in the example of  FIG.  1   , described above. In addition, recovery to local recovery machines  706   a,    706   b  . . .  706   n  may also be provided in accordance with an embodiment of the invention, as long as the local backup storage device  26 , the local recovery machines, and the recovery manager  708  are still functioning. The local backup storage device  26 , the local recovery machines, and the recovery manager  708  may be separated from the client machines  24   a,    24   b  . . .  24   n  for protection, but will not be as separated in distance as the disaster recovery site  702 . 
     In this case, the local recovery manager  708  also stores MHPs, XML files, and CAB files for the client machines  24   a,    24   b  . . .  24   n  and the local recovery machines  706   a,    706   b  . . .  706   n,  which can be generated by an MHP utility in the same manner as described above. In this example, the MHP utility may be run by the local recovery manager  708 , the local backup storage device  26 , or the individual client machines. If desired by the client system  704 , in response to a crash or disaster effecting one, some, or all of the client machines, but not the local recovery manager  708 , the local backup storage device  26 , and the local recovery machines  706   a,    706   b  . . .  706   c,  the host image may be presented to the local recovery manager  708  as one or a plurality of virtual disks, which are mounted by the local recovery manager. The local recovery manager can modify all or the appropriate host images stored on the backup storage device by running RT Convert, and assign the modified host image to a respective local recovery machine  706   a,    706   b  . . .  706   n,  where they would be booted up in a two step process using RT Rehome, as described above with respect to recovery to the remote recovery machines  18   a,    18   b  . . .  18   n.  In this case, the conformed host images are provided to respective local recovery machines across the through a network share, for example. 
     If the disaster disabled the local backup storage device  26  and/or the local recovery manager  708 , then the client system  704  would inform the remote recovery manager  16  to recover the host images of the client machines based on the host images backed up to the remote backup storage device  20 . RT Convert and RT Rehome would be run, as described above. 
     Failback to the client machines  24   a,    24   b  . . .  24   n,  the local recovery machines  706   a,    706   b  . . .  706   n,  and/or new client machines (not shown) from the disaster recovery site  702  may also be provided in accordance with embodiments of the invention, by switching the roles of the disaster recovery site  702  and the client system  704 . Failback may take place in a system configured as in  FIG.  1   , as well. After recovery, host images may be backed up to the remote backup storage device  20 . When the local backup storage device  26 , or another such backup storage device is running at the client system  704 , the remote backup storage device can backup the host images stored therein to the local backup. To failback, the local recovery manager  708  may act in the same manner the remote recovery manager  16  did for disaster recovery, using the same MHPs, XML, and CAB files for the client machines  24   a,    24   b  . . .  24   n,  or for the local recovery machines  706   a,    706   b  . . .  706   n,  which have already been prepared for disaster recovery, or new MHPs, XML, and CAB files may be prepared for new client machines. The local recovery manager  708  may then modify the host images by running RT Convert based on the MHPs so that they can run on the respective client machine (or local recovery machine), and assign the modified host images to the client machines to which failback is to take place. RT Rehome then causes a two or three step boot up, as described above with respect to recovery to the disaster recovery site, so that the host images can run on the respective client machines, local recovery machines, or new client machines at the client system  704 . 
       FIG.  11    is a block diagram of an example of an environment  800  in which the transfer of host images in accordance with embodiments of the invention takes place during migration of a host image from a first client machine to a second client machine. In this example, a first client system  800   a  includes client machines  802  . . .  802   n,  and a local backup storage device  804 . A second client system  800   b,  to which host images of the client machines  806  . . .  806   n  will be migrated, includes client machines  806  . . .  806   n,  a local backup storage device  808 , and a remote migration manager  810 . The first client machine  802  . . .  802   n  may have the same structure as the client machine  24  and may operate in the same manner, as discussed above and shown in  FIG.  4   , for example. The second client machines  806  . . .  806   n  may have the same structure and operate in the same manner as the remote recovery machine  18   a,  as discussed above and shown in  FIG.  3   . The local backup storage devices  804  and the remote backup storage device  808  may have the same structure and may be configured to operate in the same manner as the local backup storage device  60  and the remote backup storage device  20 , respectively, as discussed above and shown in  FIG.  1   . Components of the first and second client systems  800   a,    800   b  communicate with each other via a network  812 , which may comprise one or more of the networks discussed above. 
     The remote migration manager  810  may have the same structure as the remote recovery manager  16  discussed above and shown in  FIG.  2   , and may be configured to operate in the same manner as described above to migrate host images from first client machines  802  . . .  802   n  to respective second client machines  806  . . .  806   n.  For example, profile information may be collected from different types of first and second client machines, and profiles may be compared, host images may be conformed, and second client machines  806  . . .  806   n  may be configured, as described above with respect to  FIGS.  5 - 9   , by substituting the second client machines for the recovery machines in the Figures and discussion. 
     Alternative configurations described above are also applicable to this embodiment. For example, the first and second client systems  800   a,    800   b  may be configured as shown in  FIG.  10   . The second client system  800   b  and the first client system may both be at the same site, coupled via a storage area network (SAN), for example, as shown in  FIG.  10   , or at different sites. In addition, the remote migration manager  810  may be a separate processing device in the second client system  800   b  or the functions of the remote migration manager  810  may be implemented by a processing device in the remote backup storage device  808 . The functions of the remote migration manager  810  may also be performed by a separate processing device in the system  800   a,  or by a processing device of the local backup storage device  804 . 
     As above, host image migration may take place between physical-to-physical (“P2P”), virtual-to-virtual (“V2V”), virtual-to-physical (“V2P”), and physical-to-virtual (“P2V”), first client machines  802  . . .  802   n  to second client machines  802  . . .  802   n,  respectively, where the type of the recovery machine and the type of the client machine may be different and may not be known to each other or to respective first and second client systems  800   a,    800   b.    
     Migration from the first client system  800   a  to the second client system  800   b  may be conducted under the control of a job file that defines the parameters of the procedure and includes information used in the procedure, as discussed above. Since there is no failback after transfer the host images, the migrated host images are designated as main images for the purposes of disaster recovery after migration is complete, for example. Associations with the local backup storage device  804  of the first client system  800   a  may be removed. 
     Examples of implementations of embodiments of the invention are described above. Modifications may be made to those examples without departing from the scope of the invention, which is defined by the claims, below.