Systems and methods for migrating virtual machines

A computer-implemented method for migrating virtual machines may include: 1) identifying a request to migrate a virtual machine from a primary site to a secondary site, the primary site including a primary storage device used by the virtual machine and configured for asynchronous replication to a secondary storage device at the secondary site, 2) identifying a difference map that reflects differences between data on the primary storage device and the secondary storage device, 3) initiating the virtual machine at the secondary site, 4) intercepting an input/output attempt from the virtual machine at the secondary site to the secondary storage device, 5) determining, based on the difference map, that a region of the input/output attempt has not been synchronized from the primary storage device, and 6) retrieving the region from the primary storage device before allowing the input/output attempt to proceed. Various other methods, systems, and computer-readable media are disclosed.

BACKGROUND

System administrators may migrate virtual machines from one location to another in order to upgrade hardware, perform system maintenance, manage system resources, or improve virtual machine performance. In some cases, a system administrator may avoid any downtime for a virtual machine by performing a live migration (e.g., keeping the original instance of the virtual machine running until a duplicate instance is ready to take over at an alternate location). For example, the state of the virtual processor and the virtual memory of the virtual machine may be copied to a target hypervisor. Once the target hypervisor is loaded with the virtual machine, the virtual machine may continue to run as before.

However, in order to fully preserve the statefulness of the migrated virtual machine, the virtual machine may also require the same storage view. Ordinarily this may be achieved simply by directing the migrated virtual machine to the same storage device that it used before. Unfortunately, if the target location for a live migration of a virtual machine is a long distance from the original location of the virtual machine (e.g., in a different data center), the original storage device may be too far from the target location of the virtual machine, introducing unacceptable latency. Furthermore, a system administrator may wish to take the original storage device offline as well (e.g., due to an expected outage at the original data center). Accordingly, the instant disclosure addresses a need for additional and improved systems and methods for migrating virtual machines.

SUMMARY

As will be described in greater detail below, the instant disclosure generally relates to systems and methods for migrating virtual machines. Systems and methods described herein may migrate virtual machines by leveraging asynchronous replication data at a secondary site to fulfill input/output requests from an instance of the virtual machine at the secondary site when possible. These systems and methods may determine when asynchronous replication data at the secondary site is suitable for fulfilling input/output requests at the secondary site by using a difference map that identifies differences between data at the primary site and asynchronously replicated data at the secondary site.

For example, a method may include identifying a request to migrate a virtual machine from a primary site to a secondary site. As will be explained in greater detail below, the primary site may include a primary storage device used for storage by the virtual machine. The primary storage device may be configured for asynchronous replication to a secondary storage device at the secondary site. The method may also include identifying a difference map that reflects differences between data on the primary storage device and data on the secondary storage device, initiating the virtual machine at the secondary site, intercepting one or more input/output attempts from the virtual machine at the secondary site to the secondary storage device, determining, based on the difference map, that a region indicated in the input/output attempt has not yet been synchronized from the primary storage device, and then retrieving the region from the primary storage device before allowing the input/output attempt to proceed.

In another example, a system may include one or more processors configured to execute an identification module, an initiation module, an interception module, a determination module, and a retrieval module. The identification module may be programmed to identify a request to migrate a virtual machine from a primary site to a secondary site. The primary site may include a primary storage device used for storage by the virtual machine. The primary storage device may be configured for asynchronous replication to a secondary storage device at the secondary site. The identification module may also be programmed to identify a difference map that reflects differences between data on the primary storage device and data on the secondary storage device. The initiation module may be programmed to initiate the virtual machine at the secondary site. The interception module may be programmed to intercept one or more input/output attempts from the virtual machine at the secondary site to the secondary storage device. The determination module may be programmed to determine, based on the difference map, that a region indicated in the input/output attempt has not yet been synchronized from the primary storage device. The retrieval module may be programmed to retrieve the region from the primary storage device before allowing the input/output attempt to proceed.

The migration identified in the request may include a live migration; e.g., migrating the virtual machine without interrupting any service provided by the virtual machine. In some examples, the initiation module may initiate the virtual machine at the secondary site before the asynchronous replication to the secondary site is complete.

The identification module may identify the difference map in a variety of contexts. In some examples, the identification module may create the difference map. For example, the identification module may determine that output from the virtual machine at the primary site to the primary storage device is quiesced and then create the difference map before initiating the virtual machine at the secondary site. Additionally or alternatively, the identification module may create the difference map based at least in part on a log generated from the asynchronous replication. In some examples, the identification module may initialize the difference map to provisionally reflect a total difference between the data on the primary storage device and the data on the secondary storage device and then update the difference map indicating similarities between the data on the primary storage device and the data on the secondary storage device after initiating the virtual machine at the secondary site.

In some examples, the input/output attempt may include a write attempt. In these examples, the retrieval module may also modify the region with the write attempt before allowing the input/output attempt to proceed. In some examples, the retrieval module may also identify one or more additional input/output attempts from the virtual machine to the secondary storage device and determine, based on the difference map, that a region indicated in the input/output has been synchronized from the primary storage device. In these examples, the retrieval module may then allow the additional input/output attempt to proceed without interruption. In some examples, the input/output attempt may include a read attempt. In these examples, the retrieval modules may retrieve the region from the primary storage device to fulfill to read attempt.

One or more of the systems described herein may also, in some examples, create a point-in-time copy of the data on the secondary storage device before initiating the virtual machine at the secondary site.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As will be described in greater detail below, the instant disclosure generally relates to systems and methods for migrating virtual machines. Systems and methods described herein may migrate virtual machines by leveraging asynchronous replication data at a secondary site to fulfill input/output requests from an instance of the virtual machine at the secondary site when possible. These systems and methods may determine when asynchronous replication data at the secondary site is suitable for fulfilling input/output requests at the secondary site by using a difference map that identifies differences between data at the primary site and asynchronously replicated data at the secondary site.

By using a difference map to determine whether asynchronous replication data is usable by a migrated virtual machine, these systems and methods may enable system administrators to perform live migration of virtual machines over long distances (e.g., from one data center to another) while minimizing latency for input/output requests and minimizing redundant data transfer from primary to secondary sites. Embodiments of the instant disclosure may also provide various other features and advantages.

The following will provide, with reference toFIGS. 1,2, and4, detailed descriptions of exemplary systems for migrating virtual machines. Detailed descriptions of corresponding computer-implemented methods will also be provided in connection withFIG. 3. In addition, detailed descriptions of an exemplary computing system and network architecture capable of implementing one or more of the embodiments described herein will be provided in connection withFIGS. 5 and 6, respectively.

FIG. 1is a block diagram of an exemplary system100for migrating virtual machines. As illustrated in this figure, exemplary system100may include one or more modules102for performing one or more tasks. For example, and as will be explained in greater detail below, exemplary system100may include an identification module104programmed to identify a request to migrate a virtual machine from a primary site to a secondary site. The primary site may include a primary storage device used for storage by the virtual machine. The primary storage device may be configured for asynchronous replication to a secondary storage device at the secondary site. Identification module104may also be programmed to identify a difference map that reflects differences between data on the primary storage device and data on the secondary storage device. Exemplary system100may also include an initiation module106programmed to initiate the virtual machine at the secondary site. Exemplary system100may additionally include an interception module108programmed to intercept one or more input/output attempts from the virtual machine at the secondary site to the secondary storage device.

In addition, and as will be described in greater detail below, exemplary system100may include a determination module110programmed to determine, based on the difference map, that a region indicated in the input/output attempt has not yet been synchronized from the primary storage device. Exemplary system100may also include a retrieval module112programmed to retrieve the region from the primary storage device before allowing the input/output attempt to proceed. Although illustrated as separate elements, one or more of modules102inFIG. 1may represent portions of a single module or application.

Exemplary system100inFIG. 1may be deployed in a variety of ways. For example, all or a portion of exemplary system100may represent portions of exemplary system200illustrated inFIG. 2. As shown inFIG. 2, system200may include a computing system202hosting a virtual machine210in the process of a live migration to computing system206over a network204. In one embodiment, and as will be described in greater detail below, computing system206may include identification module104, initiation module106, interception module108, determination module110, and retrieval module112.

Identification module104may be programmed to migrate a virtual machine210from computing system202to computing system206, where primary storage device212may be used for storage by virtual machine210and primary storage device212may be configured for asynchronous replication to secondary storage device214. Identification module104may also be programmed to identify a difference map218that reflects differences between data on primary storage device212and data on secondary storage device214(e.g., due to a lag in asynchronous replication). Initiation module106may be programmed to initiate virtual machine210on computing system206. Interception module108may be programmed to intercept an I/O attempt216from virtual machine210on computing system206to secondary storage device214. Determination module110may be programmed to determine, based on difference map218, that a region220referred to in I/O attempt216has not yet been synchronized from primary storage device212(e.g., to secondary storage device214). Retrieval module112may be programmed to retrieve region220from primary storage device212before allowing I/O attempt216to proceed.

Computing system202generally represents any type or form of computing device capable of reading computer-executable instructions. Examples of computing system202include, without limitation, hypervisors, servers, computing clusters, laptops, desktops, cellular phones, personal digital assistants (PDAs), multimedia players, embedded systems, combinations of one or more of the same, exemplary computing system510inFIG. 5, or any other suitable computing device.

Computing system206generally represents any type or form of computing device capable of reading computer-executable instructions. Examples of computing system206include, without limitation, hypervisors, servers, computing clusters, laptops, desktops, cellular phones, personal digital assistants (PDAs), multimedia players, embedded systems, combinations of one or more of the same, exemplary computing system510inFIG. 5, or any other suitable computing device.

Primary storage device212may represent portions of a single storage device or a plurality of storage devices. In some examples, primary storage device212may also represent portions of a computing system and/or appliance configured for replicating data. Likewise, secondary storage device214may represent portions of a single storage device or a plurality of storage devices. In some examples, secondary storage device214may also represent portions of a computing system and/or appliance configured for receiving replicated data.

FIG. 3is a flow diagram of an exemplary computer-implemented method300for migrating virtual machines. The steps shown inFIG. 3may be performed by any suitable computer-executable code and/or computing system. In some embodiments, the steps shown inFIG. 3may be performed by one or more of the components of system100inFIG. 1and/or system200inFIG. 2.

As illustrated inFIG. 3, at step302one or more of the systems described herein may identify a request to migrate a virtual machine from a primary site to a secondary site. The primary site may include a primary storage device used for storage by the virtual machine and the primary storage device may be configured for asynchronous replication to a secondary storage device at the secondary site. For example, at step302identification module104may, as part of computing system206inFIG. 2, identify a request to migrate virtual machine210from computing system202to computing system206, where primary storage device212may be used for storage by virtual machine210and may be configured for asynchronous replication to secondary storage device214.

The request may include any command, instruction, and/or configuration data indicating that the migration is imminent and/or in process. Accordingly, identification module104may identify the request in a variety of ways. For example, identification module104may identify the request by receiving a message from a hypervisor, a migration appliance, and/or an application. Additionally or alternatively, identification module104may identify the request by identifying a result of the request. For example, identification module104may identify the request by identifying the transmission of the virtual machine to the secondary site and/or the installation of the virtual machine at the secondary site.

In some examples, the request may include a request to perform a live migration of the virtual machine. For example, the request may include a request to migrate the virtual machine without interrupting any service provided by the virtual machine. As used herein, the phrase “live migration” may refer to any migration and/or transfer of a virtual machine that minimizes and/or eliminates downtime for the virtual machine. For example, the phrase “live migration” may refer to statefully copying a virtual machine from a primary site to a secondary site and bringing the stateful copy of the virtual machine online (e.g., running and available for transactions) before the original instance of the virtual machine is taken offline. In some examples, the live migration may include copying an execution state (e.g., a virtual processor and the state of the virtual processor) and a memory state (e.g., a virtual random-access memory module and the state of the memory module) from the first site to the second site.

As used herein, the phrase “virtual machine” generally refers to a computing system platform that may not have direct correspondence to hardware of an underlying host machine. For example, hardware of a host system may be abstracted to a virtual machine using a hypervisor or other virtualization software. A virtual machine may run a guest operating system and/or various other software applications.

As used herein, the term “site” may refer to a geographical location, a network location, and/or a group of computing devices. The phrase “primary site” may refer to a site at which a virtual machine operates before a migration. Additionally or alternatively, “primary site” may refer to a site that includes source data (e.g., stored on a primary storage device) for an asynchronous replication scheme. Likewise, the phrase “secondary site” may refer to a site to which a virtual machine may migrate and/or operate after migration. Additionally or alternatively, “secondary site” may refer to a site that includes a replication target (e.g., a secondary storage device) for an active-passive replication scheme. In some examples, as will be described in greater detail below, the secondary storage device may, if locally mounted at the second site, function as a read-only device during replication.

As used herein, the phrase “asynchronous replication” may refer to any method and/or process of replicating data from a primary storage device to a secondary storage device where the state of replicated data on the secondary storage device does not necessarily reflect the state of data being replicated on the primary storage device. In some examples, “asynchronous replication” may refer to replication wherein a change to data on the primary storage device does not require first ensuring that the change is made to the secondary storage device, potentially resulting in the secondary storage device not reflecting the state of the primary storage device at any given moment. In some examples, the asynchronous replication may be performed on the block level. Additionally or alternatively, the asynchronous replication may be file-level replication. In some examples, the asynchronous replication may be periodic. Generally, the method of asynchronous replication is not restricted to these examples and may be performed in any other suitable manner.

As mentioned above, in some examples identification module104may identify the request for the migration by identifying the migration. In some examples, identification module104may identify the migration by performing the migration. For example, identification module104may copy the virtual machine to the secondary site. Additionally or alternatively, identification module104may perform the replication for the data used by the virtual machine from the primary site to the secondary site.

In some examples, identification module104may identify the migration as a long-distance migration. For example, identification module104may determine that the distance between the primary site and the secondary site exceeds a predetermined threshold (e.g., 200 kilometers). For example, identification module104may use IP addresses and/or other geolocation data to determine the locations of the primary and secondary sites and then calculate and/or estimate the distance. Additionally or alternatively, identification module104may determine that the data transfer latency between the primary and secondary sites exceeds a predetermined threshold. In some examples, identification module104may determine that the distance (e.g., geographical and/or in terms of latency) between the primary site and the secondary site is so great as to require asynchronous replication instead of synchronous replication between the sites. Additionally or alternatively, identification module104may simply determine that the primary site is configured to perform asynchronous replication to the secondary site.

FIG. 4is a block diagram of an exemplary system400for migrating virtual machines. As illustrated inFIG. 4, a primary site410may include a hypervisor420hosting a virtual machine430. Primary site410may also include a primary storage device440with virtual machine stored data442. A live migration452may migrate virtual machine430(with, e.g., its processor state and memory state intact) to a hypervisor470at a secondary site460via a network450. Secondary site460may also include a secondary storage device490. Primary storage device440and/or an appliance in communication with primary storage device440may be configured to replicate virtual machine stored data442to secondary storage device490, represented as an asynchronous replication454. In this manner, identification module104may identify live migration452.

Returning toFIG. 3, at step304one or more of the systems described herein may identify a difference map that reflects differences between data on the primary storage device and data on the secondary storage device. For example, at step304identification module104may, as part of computing system206inFIG. 2, identify a difference map218that reflects differences between data on primary storage device212and data on secondary storage device214. UsingFIG. 4as an additional example, at step304identification module104may identify a difference map that reflects differences between the state of virtual machine stored data422on primary storage device440and the state of virtual machine stored data422on secondary storage device490.

The difference map may include any suitable format for reflecting the differences between the virtual machine data at the primary site and the replicated virtual machine data at the secondary site. For example, the difference map may include a bitmap, where each bit represents whether a region of data between the primary and secondary sites is in sync or out of sync. As used herein, the term “region” may refer to any collection of data. Examples of regions may include blocks, sectors, regions and/or chunks of data of heterogeneous sizes. Additionally or alternatively, the difference map may include a collection of object identifiers and offset lengths indicating areas of difference between the primary and secondary sites. Generally, the difference map may include any metadata relating to the virtual machine data capable of differentiating between synchronized data and data that has yet to be synchronized.

Identification module104may identify the difference map in a variety of contexts. In some examples, identification module104may create the difference map. For example, identification module104may first determine that output from the virtual machine at the primary site to the primary storage device is quiesced and then create the difference map before initiating the virtual machine at the secondary site. In this example, identification module104may create a difference map that accurately reflects all existing differences between the primary and secondary sites. Identification module104may also update the difference map as additional data is synchronized.

In another example, identification module104may create the difference map by initializing the difference map to reflect a total difference between the data on the primary storage device and the data on the secondary storage device. For example, identification module104may initialize the difference map with all regions of data marked as out of sync between the primary and secondary sites. Identification module104may subsequently update the difference map indicating similarities between the data on the primary storage device and the data on the secondary storage device after initiating the virtual machine at the secondary site. For example, identification module104may update the difference map in the background with information on regions of virtual machine data that are in sync between the primary and secondary sites. In this manner, identification module104may expedite the live migration of the virtual machine by not requiring certain synchronization information at the time the virtual machine is initiated at the secondary site.

Identification module104may identify and/or create the difference map using any suitable source data. For example, identification module104may create the difference map based at least in part on a log generated from the asynchronous replication. For example, a block-level asynchronous replication system may maintain write-order fidelity with a sequential data log that contains updates that are yet to be replicated to the secondary site. In this example, identification module104may scan the sequential data log to determine which blocks of data have yet to be synchronized. Identification module104may then create the difference map to represent those regions of data as different between the primary and secondary sites. In another example, a block-level asynchronous replication system performing episodic and/or periodic replication may maintain metadata about changes to data at the primary site over an interval of time (e.g., as an extent list, a bitmap, etc.) In this example, identification module104may create the difference map by combining the metadata representing each interval that has not yet been received at the secondary site.

In some examples, the asynchronous replication may occur at the file-level. For example, the asynchronous replication may include a checkpoint-based periodic replication. In this example, identification module104may create the difference map by merging the metadata corresponding to each checkpoint that has yet to be replicated to the secondary site. Additionally or alternatively, identification module104may create the difference map by scanning a file change log used for the asynchronous replication. In another example, the asynchronous replication may include a file-snapshot-based periodic replication. For example, a snapshot of the data at the primary site may be implemented using a redirect-on-write mechanism (e.g., when a file is changed, create a new extent that stores new data for the files). In this example, identification module104may create the difference map based on the extents created for the snapshot which have not yet been sent to the secondary site.

Returning toFIG. 3, at step306one or more of the systems described herein may initiate the virtual machine at the secondary site. For example, at step306initiation module106may, as part of computing system206inFIG. 2, initiate virtual machine210on computing system206. UsingFIG. 4as an additional example, at step306initiation module106may initiate virtual machine430on hypervisor470.

Initiation module106may perform step306in any suitable manner. For example, initiation module106may transmit an instruction to a hypervisor at the secondary site to initiate execution of the virtual machine (e.g., as migrated from the primary site). In some examples, initiation module106may initiate the virtual machine before the asynchronous replication is complete. For example, the virtual machine may have been taken offline at the primary site, but a replication system at the primary site may not have completed the process of replicating all data and/or all recent changes to data at the primary site to the secondary site.

At step308one or more of the systems described herein may intercept one or more input/output attempts from the virtual machine at the secondary site to the secondary storage device. For example, at step308interception module108may, as part of computing system206inFIG. 2, intercept I/O attempt216from virtual machine210to secondary storage device214. UsingFIG. 4as an additional example, at step308interception module108may intercept write attempt494from virtual machine430to secondary storage device490at the point of a difference map overlay480. Difference map overlay480generally represents any use of a difference map for determining whether to permit read and/or write attempts to pass to virtual machine stored data442.

Interception module108may perform step308in a variety of ways. For example, interception module108may inject a filter driver on top of the file system used by the virtual machine for the secondary storage device. Interception module108may inject the filter driver at any suitable time, such as before the migration. The filter driver may be configured to intercept I/O operations from the virtual machine once the virtual machine is online at the secondary site. As will be described in greater detail below, the filter driver may use the difference map to resolve intercepted I/O operations. Additionally or alternatively, interception module108may intercept the input/output attempt as part of a hypervisor and/or as part of any other suitable system.

UsingFIG. 4for an example, interception module108may create a difference map overlay480between virtual machine430and secondary storage device490(e.g., by injecting the filter driver described above). Difference map overlay480may intercept a write attempt494made by virtual machine430after the live migration452to secondary site460. Difference map overlay480may also intercept a read attempt496.

Returning toFIG. 3, at step310one or more of the systems described herein may determine, based on the difference map, that a region indicated in the input/output attempt has not yet been synchronized from the primary storage device. For example, at step310determination module110may, as part of computing system206inFIG. 2, determine, based on difference map218, that region220corresponding to I/O attempt216has not yet been synchronized from the primary storage device. UsingFIG. 4as an additional example, at step310determination module110may determine, based on the difference map, that the region corresponding to write attempt494has not yet been synchronized from primary storage device440.

Determination module110may perform step310in any suitable manner, depending on the structure of the difference map. For example, if the difference map includes a bitmap of synchronized regions, determination module110may examine a bit in the difference map corresponding to the region to determine that the region has not yet been synchronized from the primary storage device.

At step312one or more of the systems described herein may retrieve the region from the primary storage device before allowing the input/output attempt to proceed. For example, at step312retrieval module112may, as part of computing system206inFIG. 2, retrieve region220from primary storage device212before allowing I/O attempt216to proceed. UsingFIG. 4as an additional example, at step312retrieval module112may determine retrieve the region corresponding to write attempt494(e.g., in a retrieval494(a)) before allowing write attempt494to proceed.

Retrieval module112may perform step312in any suitable manner. For example, retrieval module112may simply read the region from the primary storage device. In some examples, retrieval module112may also write the region to the secondary storage device (e.g., before allowing the input/output attempt to proceed). Additionally or alternatively, retrieval module112may retrieve the region for the direct fulfillment of the input/output attempt and may only write the region to the secondary storage device after and/or as a part of the fulfillment of the input/output attempt. UsingFIG. 4as an example, upon read attempt496, retrieval module112may perform a retrieval496(a) from primary storage device440. Retrieval module112may then fulfill read attempt496directly. Additionally or alternatively, retrieval module112may first write the retrieved region to secondary storage device490and then allow read attempt496to be fulfilled from secondary storage device490.

In the case that the input/output attempt is a write attempt, retrieval module112may modify the region with the write attempt before allowing the input/output attempt to proceed. For example, retrieval module112may retrieve the region from the primary storage device, modify the region with the write attempt, and then write the modified region to the secondary storage device. Additionally or alternatively, retrieval module112may retrieve the region from the primary storage device, write the region to the secondary storage device, and then allow the write attempt to proceed to the secondary storage device. UsingFIG. 4as an example, upon write attempt494, retrieval module112may perform a retrieval494(a). Retrieval module112may then modified the retrieved region with write attempt494and perform a write498. Additionally or alternatively, retrieval module112may write the retrieved region to secondary storage device490and then allow write attempt494to proceed.

In the case that the input/output attempt is a read attempt, retrieval module112may retrieve the region from the primary storage device. In some examples, retrieval module112may then fulfill the read attempt with the region. Additionally or alternatively, retrieval module112may write the region to the secondary storage device and then allow the read attempt to fetch the region from the storage device. However, even in examples in which retrieval module112directly fulfills the read attempt with the region, retrieval module112may also update the secondary storage device (and the difference map) with the region.

After retrieving the region and updating the secondary storage device with the region, in some examples retrieval module112may update the difference map to reflect that the region has been synchronized at the secondary site. After step312, method300may terminate.

In some examples, one or more of the systems described herein may process an input/output attempt pertaining to a region that has already been synchronized to the secondary site. For example, identification module104may identify one or more additional input/output attempts from the virtual machine to the secondary storage device (using, e.g., any of the techniques described earlier). Determination module110may determine, based on the difference map, that a region indicated in the input/output attempt has been synchronized from the primary storage device (again, using any of the techniques described earlier). The systems described herein may then allow the additional input/output attempt to proceed without interruption. For example, the additional input/output attempt may operate on the secondary storage device without waiting for a retrieval from the primary storage device.

In some examples, one or more of the systems described herein may create a point-in-time copy of the data on the secondary storage device before initiating the virtual machine at the secondary site. For example, if the primary site lost operational capacity before the migration of the virtual machine was complete, the systems described herein may discard the incompletely synchronized data at the secondary site and restore the point-in-time copy to the secondary storage device to try the migration process again.

By using a difference map to determine whether asynchronous replication data is usable by a migrated virtual machine, these systems and methods may enable system administrators to perform live migration of virtual machines over long distances (e.g., from one data center to another) while minimizing latency for input/output requests and minimizing redundant data transfer from primary to secondary sites.

FIG. 5is a block diagram of an exemplary computing system510capable of implementing one or more of the embodiments described and/or illustrated herein. Computing system510broadly represents any single or multi-processor computing device or system capable of executing computer-readable instructions. Examples of computing system510include, without limitation, workstations, laptops, client-side terminals, servers, distributed computing systems, handheld devices, or any other computing system or device. In its most basic configuration, computing system510may include at least one processor514and a system memory516.

Processor514generally represents any type or form of processing unit capable of processing data or interpreting and executing instructions. In certain embodiments, processor514may receive instructions from a software application or module. These instructions may cause processor514to perform the functions of one or more of the exemplary embodiments described and/or illustrated herein. For example, processor514may perform and/or be a means for performing, either alone or in combination with other elements, one or more of the identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying steps described herein. Processor514may also perform and/or be a means for performing any other steps, methods, or processes described and/or illustrated herein.

In certain embodiments, exemplary computing system510may also include one or more components or elements in addition to processor514and system memory516. For example, as illustrated inFIG. 5, computing system510may include a memory controller518, an input/output (I/O) controller520, and a communication interface522, each of which may be interconnected via a communication infrastructure512. Communication infrastructure512generally represents any type or form of infrastructure capable of facilitating communication between one or more components of a computing device. Examples of communication infrastructure512include, without limitation, a communication bus (such as an ISA, PCI, PCIe, or similar bus) and a network.

Memory controller518generally represents any type or form of device capable of handling memory or data or controlling communication between one or more components of computing system510. For example, in certain embodiments memory controller518may control communication between processor514, system memory516, and I/O controller520via communication infrastructure512. In certain embodiments, memory controller518may perform and/or be a means for performing, either alone or in combination with other elements, one or more of the steps or features described and/or illustrated herein, such as identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying.

I/O controller520generally represents any type or form of module capable of coordinating and/or controlling the input and output functions of a computing device. For example, in certain embodiments I/O controller520may control or facilitate transfer of data between one or more elements of computing system510, such as processor514, system memory516, communication interface522, display adapter526, input interface530, and storage interface534. I/O controller520may be used, for example, to perform and/or be a means for performing, either alone or in combination with other elements, one or more of the identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying steps described herein. I/O controller520may also be used to perform and/or be a means for performing other steps and features set forth in the instant disclosure.

In certain embodiments, communication interface522may also represent a host adapter configured to facilitate communication between computing system510and one or more additional network or storage devices via an external bus or communications channel. Examples of host adapters include, without limitation, SCSI host adapters, USB host adapters, IEEE 1394 host adapters, SATA and eSATA host adapters, ATA and PATA host adapters, Fibre Channel interface adapters, Ethernet adapters, or the like. Communication interface522may also allow computing system510to engage in distributed or remote computing. For example, communication interface522may receive instructions from a remote device or send instructions to a remote device for execution. In certain embodiments, communication interface522may perform and/or be a means for performing, either alone or in combination with other elements, one or more of the identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying steps disclosed herein. Communication interface522may also be used to perform and/or be a means for performing other steps and features set forth in the instant disclosure.

As illustrated inFIG. 5, exemplary computing system510may also include at least one input device528coupled to communication infrastructure512via an input interface530. Input device528generally represents any type or form of input device capable of providing input, either computer or human generated, to exemplary computing system510. Examples of input device528include, without limitation, a keyboard, a pointing device, a speech recognition device, or any other input device. In at least one embodiment, input device528may perform and/or be a means for performing, either alone or in combination with other elements, one or more of the identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying steps disclosed herein. Input device528may also be used to perform and/or be a means for performing other steps and features set forth in the instant disclosure.

In certain embodiments, storage devices532and533may be used, for example, to perform and/or be a means for performing, either alone or in combination with other elements, one or more of the identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying steps disclosed herein. Storage devices532and533may also be used to perform and/or be a means for performing other steps and features set forth in the instant disclosure.

FIG. 6is a block diagram of an exemplary network architecture600in which client systems610,620, and630and servers640and645may be coupled to a network650. Client systems610,620, and630generally represent any type or form of computing device or system, such as exemplary computing system510inFIG. 5. In one example, client system610may include system100fromFIG. 1.

Similarly, servers640and645generally represent computing devices or systems, such as application servers or database servers, configured to provide various database services and/or run certain software applications. Network650generally represents any telecommunication or computer network including, for example, an intranet, a wide area network (WAN), a local area network (LAN), a personal area network (PAN), or the Internet.

As illustrated inFIG. 6, one or more storage devices660(1)-(N) may be directly attached to server640. Similarly, one or more storage devices670(1)-(N) may be directly attached to server645. Storage devices660(1)-(N) and storage devices670(1)-(N) generally represent any type or form of storage device or medium capable of storing data and/or other computer-readable instructions. In certain embodiments, storage devices660(1)-(N) and storage devices670(1)-(N) may represent network-attached storage (NAS) devices configured to communicate with servers640and645using various protocols, such as NFS, SMB, or CIFS.

In at least one embodiment, all or a portion of one or more of the exemplary embodiments disclosed herein may be encoded as a computer program and loaded onto and executed by server640, server645, storage devices660(1)-(N), storage devices670(1)-(N), storage devices690(1)-(N), intelligent storage array695, or any combination thereof. All or a portion of one or more of the exemplary embodiments disclosed herein may also be encoded as a computer program, stored in server640, run by server645, and distributed to client systems610,620, and630over network650. Accordingly, network architecture600may perform and/or be a means for performing, either alone or in combination with other elements, one or more of the identifying, performing, determining, creating, initializing, updating, initiating, intercepting, determining, retrieving, and/or modifying steps disclosed herein. Network architecture600may also be used to perform and/or be a means for performing other steps and features set forth in the instant disclosure.

In addition, one or more of the modules described herein may transform data, physical devices, and/or representations of physical devices from one form to another. For example, one or more of the modules described herein may transform a computing device into a device for efficiently migrating virtual machines.