Patent Publication Number: US-11379246-B2

Title: Automatic configuration of multiple virtual storage processors

Description:
TECHNICAL FIELD 
     The disclosed technology relates generally to systems with multiple virtual storage processors, and more specifically to technology for providing automatic configuration of multiple virtual storage processors in a virtual storage appliance. 
     BACKGROUND 
     Data storage appliances (“storage appliances”) may be arrangements of hardware and software that include non-volatile data storage devices (e.g. electronic flash drives, magnetic disk drives, and/or optical drives) that are used to provide non-volatile storage for processing I/O (Input/Output) requests (i.e. writes and/or reads) that are received from one or more applications. The I/O requests that are processed by a storage appliance may include block I/O requests as well as file I/O requests. The I/O requests indicate data that is stored in storage objects (e.g. block based and/or file based storage objects) that are maintained within the storage appliance. The storage appliance performs various data storage services that organize and secure data received from the applications. 
     SUMMARY 
     Cloud computing technology is often relied on to meet the computing needs of users and organizations. In a cloud computing environment, applications that issue I/O requests may execute in virtual machines that run on one or more hypervisors executing on one or more host computers. In such contexts, it is sometimes desirable for storage appliances to also be virtualized, e.g. as virtual storage appliances (VSAs) that also execute in virtual machines. It may further be desirable to provide high availability by combining multiple (e.g. two or more) virtual storage processors within a virtual storage appliance, so that a non-failing virtual storage processor can be used to seamlessly continue the processing of I/O requests in the event of a failure occurring in one of the other virtual storage processors, and such that the continuous processing of I/O requests is not significantly interrupted or delayed. 
     The hypervisor or hypervisors on which the virtual storage appliance executes provide virtual hardware resources, including virtual data storage resources that are consumed by the virtual storage processors while they process I/O requests. The properties of the virtual resources provided by a hypervisor may vary depending on the specific configuration and/or capabilities of the underlying hardware resources on which the hypervisor operates. For example, one hypervisor may operate using underlying non-volatile data storage devices that provide data redundancy protection, e.g. by way of Redundant Array of Independent Disks (RAID) technology or the like implemented within the non-volatile data storage devices. In such a configuration, the virtual resources provided by the hypervisor are allocated from non-volatile data storage devices that provide data redundancy protection. In contrast, another hypervisor may operate using underlying non-volatile data storage devices that do not provide data redundancy protection. In that type of configuration, the virtual resources provided by the hypervisor are not allocated from non-volatile data storage devices that provide data redundancy protection. Without knowledge of such properties of the virtual resources provided by the hypervisor, the virtual storage processors cannot be correctly configured for all hypervisor configurations on which the virtual storage appliance may be deployed. For example, if virtual storage processors are statically configured to always provide RAID data protection with regard to the data stored in the storage objects that they make accessible to consumer applications, regardless of the properties of the virtual resources provided to the virtual storage processors by the hypervisor, then any virtual storage processors that are deployed on hypervisors that provide virtual resources from underlying non-volatile data storage devices with RAID protection may be considered inefficient and wasteful, because of the duplicative and/or unneeded RAID protection that they provide. Alternatively, if virtual storage processors are statically configured to not provide RAID data protection, e.g. based on an assumption that the underlying non-volatile data storage devices used by the hypervisor do provide data redundancy protection, deployment of virtual storage processors on hypervisors that use underlying non-volatile data storage devices that are not configured to provide RAID data protection would potentially result in a level of data protection that is considered lower than is desirable or expected. While data redundancy protection is one example of a data service that may or may not be provided by underlying non-volatile data storage devices, other examples of a data service that may or may not be provided by underlying non-volatile data storage devices include data deduplication, data compression, and/or data encryption. 
     Other technical problems may also occur when deploying a virtual storage appliance having multiple virtual storage processors in a virtualized execution environment. For example, multiple virtual storage processors may require the capability to communicate privately with each other, e.g. in order to provide high availability to the application(s) issuing I/O requests. In non-virtualized environments, in which multiple physical storage processors communicate within a physical data storage appliance in order to provide high availability, such private intra-storage appliance communication may be provided using a dedicated communication media that physically interconnects the multiple physical storage appliances. However, in a virtualized execution environment in which each one of the multiple virtual storage processors is embodied as virtual machine, no such dedicated physical communication media is available to provide private intra-storage appliance communications. 
     Technology is disclosed herein that addresses the above described and other technical problems of previous solutions. In the disclosed technology, a virtual storage appliance having multiple virtual storage processors is installed in a virtualized execution environment. Each one of the virtual storage processors may be a virtual machine that executes in the virtualized execution environment. At the time the virtual storage appliance is installed, properties of virtual resources provided by the virtualized execution environment to the virtual storage processors are obtained. The virtual resources are subsequently consumed by the virtual storage processors while processing Input/Output (I/O) requests received from at least one application. The virtual storage processors are automatically configured in response to the properties of the virtual resources provided by the virtualized execution environment. 
     In some embodiments, a virtual private network may be created between the virtual storage processors within the virtualized execution environment. The virtual private network enables the virtual storage processors to securely share data with each other. The data shared between the virtual storage processors over the virtual private network may be used, by one of the virtual storage processors that continues functioning after another one of the virtual storage processors fails, in order to continue processing I/O requests received from the application on the one of the virtual storage processors that continues functioning after the failure. 
     In some embodiments, the properties of the virtual resources provided by the virtualized execution environment that are obtained at the time the virtual storage appliance is installed may include an indication of whether the virtual resources provided by the virtualized execution environment to the virtual storage processors are allocated from one or more physical hardware non-volatile data storage devices that provide data redundancy protection. 
     In some embodiments, the properties that are obtained at the time the virtual storage appliance is installed may include an indication that the virtual resources provided by the virtualized execution environment to the virtual storage processors are allocated from one or more physical hardware non-volatile data storage devices that do not provide data redundancy protection. In such embodiments, the virtual storage processors, in response to the indication that the virtual resources provided by the virtualized execution environment to the virtual storage processors are allocated from one or more physical hardware non-volatile data storage devices that do not provide data redundancy protection, the virtual storage processors may be automatically configured at least in part by configuring a software stack in each virtual storage processor that processes I/O requests received from the application such that the software stack provides data redundancy protection for data received from the consumer application. 
     In some embodiments, the properties that are obtained at the time the virtual storage appliance is installed include an indication that the virtual resources provided by the virtualized execution environment to the virtual storage processors are allocated from one or more physical hardware non-volatile data storage devices that do provide data redundancy protection. In such embodiments, in response to the indication that the virtual resources provided by the virtualized execution environment to the virtual storage processors are allocated from one or more physical hardware non-volatile data storage devices that do provide data redundancy protection, the virtual storage processors may be automatically configured at least in part by configuring a software stack in each virtual storage processor that processes I/O requests received from the application such that the software stack does not provide data redundancy protection for data received from the consumer application. 
     In some embodiments, a cache of data received from the application may be replicated on each one of the virtual storage processors. In such embodiments, the replication of the cache of data received from the application on each one of the virtual storage processors may be performed over the virtual private network created between the virtual storage processors. 
     In some embodiments, the virtual resources provided by the virtualized execution environment to the virtual storage processors may be consumed by the virtual storage processors at least in part while the virtual storage processors process both block I/O requests and file I/O requests that are received by the virtual storage processors from the consumer application. 
     In some embodiments, the application may be a virtual machine that executes in the virtualized execution environment. 
     Embodiments of the disclosed technology may provide significant improvements over previous technologies. For example, embodiments of the disclosed technology enable multiple virtual storage processors to be automatically configured based on the properties of the virtual resources provided by one or more hypervisors in a virtualized execution environment, thus avoiding inefficient and/or wasteful configurations, while also avoiding the undesirable result of providing less data services (e.g. a lower level of protection) than is expected. In addition, some embodiments may advantageously provide secure communications within the virtual storage appliance communication by creating a virtual private network between the multiple virtual storage processors, since dedicated hardware interconnect(s) between virtual storage processors may not be available in virtualized execution environments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features and advantages will be apparent from the following description of particular embodiments of the disclosed technology, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of various embodiments of the disclosed technology. 
         FIG. 1  is a block diagram showing an example of components in some embodiments and an operational environment; 
         FIG. 2  is a block diagram showing a first example of automatically configuring multiple virtual storage processors in response to the properties of virtual resources that are provided to and consumed by the virtual storage processors while processing I/O requests received from at least one application; 
         FIG. 3  is a block diagram showing a second example of automatically configuring multiple virtual storage processors in response to the properties of virtual resources that are provided to and consumed by the virtual storage processors while processing I/O requests received from at least one consumer application; and 
         FIG. 4  is a flow chart showing an example of steps that may be performed in some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the invention will now be described. The embodiments described herein are only examples of how features and principles of the invention may be embodied. The invention itself is accordingly broader than the specific examples described below. 
     The disclosed technology includes a virtual storage appliance having multiple virtual storage processors. The virtual storage appliance is installed in a virtualized execution environment. The virtualized execution environment may include or consist of one or more hypervisors executing on one or more host server computers, and the multiple virtual storage processors may each execute as a virtual machine within the virtualized execution environment. At the time the virtual storage appliance is installed (e.g. at the time the virtual storage appliance is first booted up in the virtualized execution environment), the virtual storage processors obtain properties of virtual resources that are provided by the virtualized execution environment to the virtual storage processors. The properties of the virtual resources may, for example, reflect the configuration and/or capabilities of non-volatile data storage devices from which the virtual resources are allocated. The virtual storage processors subsequently consume the virtual resources provided by the virtualized execution environment while processing Input/Output (I/O) requests that are received by the virtual storage processors from at least one consumer application, e.g. by storing data received in write I/O requests received from the application in portions of non-volatile data storage allocated to the virtual resources provided to the virtual storage processors by the virtualized execution environment. The virtual storage processors are automatically configured in response to the properties of the virtual resources provided by the virtualized execution environment that are obtained at the time the virtual storage appliance is installed. In some embodiments, a virtual private network may be created between the virtual storage processors within the virtualized execution environment, in order for the virtual storage processors to securely share data with each other that may be used by one of the virtual storage processors that continues functioning after another one of the virtual storage processors fails, in order to seamlessly continue the processing of I/O requests received from the application on the one of the virtual storage processors that continues functioning after the failure. 
       FIG. 1  shows an example of an environment in which embodiments of the disclosed technology may operate, and an illustrative embodiment of the disclosed technology.  FIG. 1  shows an operational environment that includes Host Computers  100 , which may be embodied as one or more server computers. For example, the Host Computers  100  and Non-Volatile Data Storage Devices  106  may be embodied together as a number of networked hardware computing and data storage elements located within a cloud infrastructure. The Host Computers  100  include Processing Circuitry  102 , Communication Devices/Interfaces  104 , and Memory  105 . Processing Circuitry  102  may be embodied as one or more hardware processors that are capable of reading and executing threads of program instructions as they are scheduled for execution. Communication Devices/Interfaces  104  may be embodied as network interface adapters, SCSI initiators, SCSI targets, etc., that operate at least in part by converting electronic and/or optical signals received over one or more computer and/or communication networks that interconnect Host Computers  100  and/or Non-Volatile Data Storage Devices  106  into electronic form for internal use by Host Computers  100 . In some embodiments, the Communication Devices/Interfaces  104  may include one or more physical communication/networking devices that interconnect the server computers in Host Computers  100  and/or Non-Volatile Data Storage Devices  106 , such as physical network switches, routers, etc. Memory  105  may be embodied as volatile memory (e.g., RAM), and/or non-volatile memory (e.g. ROM, disk drives, solid state drives, etc.). Memory  105  is communicably connected to Processing Circuitry  102 , and stores executable program code instructions that are executed on Processing Circuitry  102 . As illustrated in  FIG. 1 , Memory  105  stores specialized software components and/or data structures that may be provided at least in part in the form of executable program instructions. When the executable instructions of the software components shown in  FIG. 1  (e.g. Virtualized Execution Environment  110 , Virtual SP- 1   116 , Virtual SP- 2   118 , and Data Storage Service Consumer Application(s)  150 ) are executed by Processing Circuitry  102 , the methods and functionalities of the software described herein are performed. Although certain specific software constructs are shown in  FIG. 1  and described herein, those skilled in the art will recognize that Memory  105  may further include various other types of software constructs, which are not shown. 
     Non-Volatile Data Storage Devices  106  may include or consist of some number of physical hardware disk drives. The disk drives in Non-Volatile Data Storage Devices  106  may include magnetic disk drives, electronic flash drives, optical drives, and/or other types of non-volatile data storage drives or devices. Non-Volatile Data Storage Devices  106  may further include communication interfaces, e.g. network interface adapters, SCSI targets, etc., that enable Non-Volatile Data Storage Devices  106  to be accessed by Host Computers  100  over one or more computer and/or communication networks. Non-Volatile Data Storage Devices  106  may or may not be capable of and/or configured to provide various types of data services with regard to the data stored on the disks within Non-Volatile Data Storage Devices  106 , and accordingly for data that is stored on the Virtual Resources  112  that are allocated by Virtualized Execution Environment  110  from Non-Volatile Data Storage Devices  106 . For example, Non-Volatile Data Storage Devices  106  may be configured to provide data redundancy protection. For example, in some configurations, Non-Volatile Data Storage Devices  106  may include data redundancy protection for the data written by Host Computers  100  to the physical disks within Non-Volatile Data Storage Devices  106 , and accordingly for data stored on the Virtual Resources  112 , e.g. by way of Redundant Array of Independent Disks (RAID) technology or the like that is provided within the Non-Volatile Data Storage Device  106 . Other examples of data services that may or may not be provided by Non-Volatile Data Storage Devices  106  include data deduplication, data compression, and/or data encryption. 
     As shown in  FIG. 1 , the software components in Memory  105  include a Virtualized Execution Environment  110 . Virtualized Execution Environment  110  may include or consist of one or more hypervisors. Virtual Execution Environment  110  provides Virtual Resources  112  to some number of virtual machines that are also stored in Memory  105 , and that also execute on Virtualized Execution Environment  110 . For example, the Virtual Resources  112  may include or consist of some number of virtual disks that each consist of non-volatile data storage allocated from the Non-Volatile Data Storage Devices  106 , as shown for purposes of illustration in  FIG. 1  by Virtual Disks  114 . While virtual disks are one example of the data storage resources in Virtual Resources  112  that may be provided by the Virtualized Execution Environment  112  to Virtual SP-A  116  and Virtual SP-B  118 , the disclosed virtual storage processors may be embodied to consume, and the virtualized execution environment may provide, various other specific types of data storage resources, virtual and otherwise, that are additionally or alternatively provided to the virtual storage processors, e.g. by the Virtualized Execution Environment  110  in Virtual Resources  112  or otherwise. Such other types of data storage resources that may be provided to and consumed by the virtual storage processors include without limitation i) Physical RDMs (“Raw Device Mappings”) through which the Virtualized Execution Environment  110  may provide physical disks or logical units (“LUNs”) of non-volatile data storage to the virtual storage processors, ii) iSCSI block LUNs provided from an external data storage array or the like that can be consumed by the virtual storage processors as shared data storage, and/or iii) files provided as disk objects, e.g. a filesystem may be created and mounted on the Virtual Storage Appliance  175 , and then the virtual storage processors may consume files as disk objects. 
     The virtual machines that execute on Virtualized Execution Environment  110  include multiple virtual storage processors within the Virtual Storage Appliance  175 . For example, as shown in  FIG. 1 , the virtual machines that execute on Virtualized Execution Environment  110  include a first virtual storage processor Virtual SP- 1   116  and a second virtual storage processor Virtual SP- 2   118 . Each one of the virtual storage processors executing on Virtualized Execution Environment  110  includes an I/O request processing stack that processes I/O requests, communication logic that establishes one or more virtual private networks between the virtual storage processors, and failure detection logic that detects when one of the virtual storage processors fails. For example, Virtual SP- 1   116  includes I/O Request Processing Stack  126 , Intra-VSA Communication Logic  120 , Failure Detection Logic  122 , and Configuration Logic  124 , and Virtual SP- 2   118  includes I/O Request Processing Stack  140 , Intra-VSA Communication Logic  134 , Failure Detection Logic  136 , and Configuration Logic  138 . 
     The virtual machines that execute on Virtualized Execution Environment  110  also include one or more applications that consume data storage services that are provided by the virtual storage processors in Virtual Storage Appliance  175 . For example, as shown in  FIG. 1 , Data Storage Service Consumer Application(s)  150  may consist of or include one or more applications that each execute as a virtual machine on Virtualized Execution Environment  110 . Data Storage Service Consumer Application(s)  150  may logically connect to and communicate with one or both of Virtual SP- 1   116  and/or Virtual SP- 2   118  in order to communicate block and/or file based I/O Requests  152  to Virtual SP- 1   116  and/or Virtual SP- 2   118 . For example, I/O Requests  152  communicated from Data Storage Service Consumer Application(s)  150  to Virtual SP- 1  and/or Virtual SP- 2   118  may include block I/O requests (read requests and/or write requests) that are conveyed from Data Storage Service Consumer Application(s)  150  to Virtual SP- 1   116  and/or Virtual SP- 2   118  using block storage interfaces and protocols such as, for example, the Small Computer System Interface (SCSI), Fibre Channel (FC), Serial Attached SCSI (SAS), Internet Small Computer System Interface (iSCSI), and/or other block storage interfaces and/or protocols. I/O Requests  152  communicated from Data Storage Service Consumer Application(s)  150  to Virtual SP- 1   116  and/or Virtual SP- 2   118  may also or alternatively include file I/O requests (read requests and/or write requests) communicated from Data Storage Service Consumer Application(s)  150  to Virtual SP- 1   116  and/or Virtual SP- 2   118  using file storage interfaces and protocols such as, for example, the Network File System (NFS) distributed file system protocol, the Server Message Block (SMB)/Common Internet File System (CIFS) application-layer network protocol, Apple Filing Protocol (AFP), and/or other file storage interfaces and/or protocols. Virtual SP- 1   116  and/or Virtual SP- 2   118  may accordingly be configured to receive host I/O requests through block-based and/or file-based storage protocols, and to respond to host I/O requests of either type by reading or writing logical units of non-volatile data storage that are allocated from at least portions of one or more virtual resources that are provided to Virtual SP- 1   116  and/or Virtual SP- 2   118  by Virtualized Execution Environment  110 . 
     For example, the I/O request processing stack in each one of Virtual SP- 1   116  and Virtual SP- 2   118  may provide layers of program logic for processing and/or supporting the processing of I/O Requests  152 . Those of I/O Requests  152  that are directed to and received by Virtual SP- 1   116  may be processed by I/O Request Processing Stack  126 , and those of I/O Requests  152  that are directed to and received by Virtual SP- 2   118  may be processed by I/O Request Processing Stack  140 . In some configurations, I/O Requests  152  may be distributed across both Virtual SP- 1   116  and Virtual SP- 2   118  while Virtual SP- 1   116  and Virtual SP- 2   118  are both functional, e.g. in order to provide load balancing. In the event that one of either Virtual SP- 1   116  or Virtual SP- 2   118  individually fails, the other virtual storage processor that remains functional continues to process I/O Requests  152  without interruption, thereby providing high availability of data storage services from Virtual Storage Appliance  175  to Data Storage Service Consumer Application(s)  150 . Alternatively, I/O Requests  152  may be initially processed by Virtual SP- 1   116 , until Virtual SP- 1   116  fails, after which Virtual SP- 2   118  seamlessly continues the processing of I/O Requests  152  without interruption of data storage services provided by Virtual Storage Appliance  175  to Data Storage Service Consumer Application(s)  150 . 
     I/O requests received by Virtual SP- 1   116  and processed by I/O Request Processing Stack  126 , and I/O requests received by Virtual SP- 2   118  and processed by I/O Request Processing Stack  140  may include I/O read requests and I/O write requests directed to various types of block data objects that are provided by Virtual SP- 1   116  and/or Virtual SP- 2   118  to Data Storage Service Consumer Application(s)  150  using portions of non-volatile data storage that are allocated from Virtual Resources  112 . Such block data objects may include or consist of logical disks (e.g. logical units sometimes referred to as LUNs) and/or block-based virtual volumes (VVols) that are accessed by Data Storage Service Consumer Application(s)  150 . 
     I/O requests received by Virtual SP- 1   116  and processed by I/O Request Processing Stack  126 , and I/O requests received by Virtual SP- 2   118  and processed by I/O Request Processing Stack  140  may also or alternatively include I/O read requests and I/O write that are directed to file data objects provided by Virtual SP- 1   116  and/or Virtual SP- 2   118  to Data Storage Service Consumer Application(s)  150  using non-volatile data storage allocated from Virtual Resources  112 , such as files or file systems that are accessed by Data Storage Service Consumer Application(s)  150 . 
     At the time that Virtual Storage Appliance  175  is installed, properties of Virtual Resources  112  are obtained. For example, at the time Virtual Storage Appliance  175  is first booted up on Virtualized Execution Environment  110 , Virtual SP- 1   116  and/or Virtual SP- 2   118  may issue a query to obtain some number of relevant properties of Virtual Resources  112 , as illustrated by Query  130 . For example, the query may be issued by Virtual SP- 1   116  and/or Virtual SP- 2   118  to the Virtualized Execution Environment  110 , as shown in  FIG. 1 , or alternatively to the Non-Volatile Data Storage Devices  106 , or alternatively to a system administration system or to a system administrator user. The response to the query indicates to Virtual SP- 1   116  and/or Virtual SP- 2   118  one or more properties of the Virtual Resources  112  that are provided by Virtualized Execution Environment  110  to Virtual SP- 1   116  and/or Virtual SP- 2   118 , and is shown for purposes of illustration by Virtual Resource Properties  132 . The properties returned may include properties of the Virtual Disks  114  and/or properties of other specific types of data storage resources in Virtual Resources  112  that are consumed by Virtual SP- 1   116  and/or Virtual SP- 2   118 . Properties of the Virtual Resources  112  may include an indication of whether one or more data services are provided by the physical hardware storage devices from which Virtual Resources  112  are allocated by the Virtualized Execution Environment  110 , e.g. indications of whether or not one or more data services are provided by Non-Volatile Data Storage Devices  106  for data that is stored in the Virtual Resources  112 . Such properties may, for example, indicate whether or not Non-Volatile Data Storage Devices  106  provide one or more data services such as data redundancy protection (i.e. RAID protection), data deduplication, data compression, and/or data encryption. Query  130  may be issued, and Virtual Resource Properties  132  may be received, by Configuration Logic  124  in Virtual SP- 1   116  and/or by Configuration Logic  138  in Virtual SP- 2   118 . 
     The Virtual Resources  112  provided by Virtualized Execution Environment  110  to Virtual SP- 1   116  and Virtual SP- 2   118  are subsequently consumed by Virtual SP- 1   116  and/or Virtual SP- 2   118  while Virtual SP- 1   116  and/or Virtual SP- 2   118  process I/O Requests  152  that are received by Virtual SP- 1   116  and/or Virtual SP- 2   118  from Data Storage Service Consumer Application(s)  150 . For example, I/O Request Processing Stack  126  in Virtual SP- 1   116  and/or I/O Request Processing Stack  140  in Virtual SP- 2   118  may allocate non-volatile data storage from one or more of Virtual Disks  114  and/or other specific types of data storage resources in Virtual Resources  112  for use in one or more data objects, and then store data into those data objects that is indicated by some number of write requests within I/O Requests  152  while processing those write requests. 
     Further at the time that Virtual Storage Appliance  175  is installed (e.g. at the time that Virtual Storage Appliance  175  is first booted up on Virtualized Execution Environment  110 ), I/O Request Processing Stack  126  and/or I/O Request Processing Stack  140  are automatically configured in response to the properties of Virtual Resources  112  that are provided to Virtual SP- 1   116  and/or Virtual SP- 2   118 , e.g. by Virtualized Execution Environment  110 . For example, Configuration Logic  124  may configure I/O Request Processing Stack  126  based on the Virtual Resource Properties  132 , and/or Configuration Logic  138  may configure I/O Request Processing Stack  140  based on Virtual Resource Properties  132 , also at the time that Virtual Storage Appliance  175  is installed. For example, in the event that Virtual Resource Properties  132  indicates that a specific data service (e.g. data redundancy protection, data deduplication, data compression, or data encryption) is not provided by Non-Volatile Data Storage Devices  106 , then Configuration Logic  124  may configure I/O Request Processing Stack  126  to include and/or execute program logic that provides that data service for data indicated by I/O Requests  152  that are directed to and processed by Virtual SP- 1   116 , and/or Configuration Logic  138  may configure I/O Request Processing Stack  140  to include and/or execute program logic that provides that data service for data indicated by I/O Requests  152  that are directed to and processed by Virtual SP- 2   118 . 
     In some embodiments, one or more virtual private networks may be created between Virtual SP- 1   116  and Virtual SP- 2   118  within the Virtualized Execution Environment  110 , shown for purposes of illustration in  FIG. 1  by VLAN(s)  128 . The VLAN(s)  128  enable Virtual SP- 1   116  and Virtual SP- 2   118  to securely share data with each other, and may be created by Intra-VSA Communication Logic  120  and Intra-VSA Communication Logic  134 . For example, data shared between Virtual SP- 116  and Virtual SP- 2   118  over VLAN(s)  128  may be used by one of Virtual SP- 1   116  or Virtual SP- 2   118  after the other virtual storage processor fails, in order to continue processing I/O Requests  152  without interruption. In some embodiments, VLAN(s)  128  may be created in whole or in part using the Secure Shell (SSH) cryptographic network protocol for operating network services securely over an unsecured network. In some embodiments, VLAN(s)  128  may include and/or span one or more virtual switches (sometimes referred to as “vSwitches”) and/or virtual network interface controllers (sometimes referred to as “vNICs”), that may be provided by Virtualized Execution Environment  110 . VLAN(s)  128  may also include and/or span one or more physical network switches or the like that interconnect server computers within Host Computers  100  in the event that Virtual SP- 1   116  and Virtual SP- 2   118  execute on different server computers. VLANs  128  may be embodied as any form of data communication that may be established between Virtual SP- 1   116  and Virtual SP- 2   118 , including but not limited to communications between Virtual SP- 1   116  and Virtual SP- 2   118  that is performed by way of virtual RDMA (Remote Direct Memory Access) or the like. 
     In some embodiments, a cache of data received from Data Storage Service Consumer Application(s)  150  may be replicated between Virtual SP- 1   116  and Virtual SP- 2   118 , such that I/O Request Processing Stack  126  and I/O Request Processing Stack  140  each maintain an identical cache. In some embodiments, the cache may be replicated between Virtual SP- 1   116  and Virtual SP- 2   118  over VLAN(s)  128 . The replicated cache may store data indicated by write requests in I/O Requests  152 . Each such write request may specify a data object, and indicate (or include) host I/O data that is to be written to the specified data object. For each one of the write requests, the indicated data may initially be stored in the replicated cache on both Virtual SP- 1   116  and Virtual SP- 2   118  when the write request is received by Virtual SP- 1   116  or Virtual SP- 2   118 . Virtual SP- 1   116  and/or Virtual SP- 2   118  may then provide an acknowledgment to Data Storage Service Consumer Application(s)  150  once the data indicated by the write request has been securely stored in the replicated cache, indicating successful completion of the write request. In addition, in some embodiments, data indicated for retrieval by one or more read requests in I/O Requests  152  may also be accumulated over time in the replicated cache. By replicating the cache in both Virtual SP- 1   116  and Virtual SP- 2   118  over VLAN(S)  152 , embodiments of the disclosed technology provide for rapid failover between Virtual SP- 1   116  and Virtual SP- 2   118  in the event of a failure of one of Virtual SP- 1   116  or Virtual SP- 2   118 , without interrupting the processing of I/O Requests  152 . 
     VLAN(s)  128  may also be used to share other types of data between Virtual SP- 1   116  and Virtual SP- 2   118 . For example, in some embodiments, Failure Detection Logic  122  and Failure Detection Logic  136  may operate to periodically send heartbeat signals to each other over VLAN(s)  128  in order for Virtual SP- 1   116  and Virtual SP- 2   118  to detect when the other virtual storage processor has failed. In such embodiments, for example, if Failure Detection Logic  136  does not receive a heartbeat signal from Failure Detection Logic  122  within some predetermined period of time, then Failure Detection Logic  136  detects that Virtual SP- 2   118  has failed, and that accordingly Virtual SP- 2   118  should process all of I/O Requests  152  going forward. Similarly, in another example, if Failure Detection Logic  122  does not receive a heartbeat signal from Failure Detection Logic  136  within some predetermined period of time, then Failure Detection Logic  122  may detect that Virtual SP- 2   118  has failed, and that accordingly Virtual SP- 1   116  should process all of I/O Requests  152  going forward. 
     As shown in  FIG. 1 , Virtual Resources  112  provided by Virtualized Execution Environment  110  (e.g. Virtual Disks  114 , etc.) may be made up of non-volatile data storage allocated by Virtualized Execution Environment  110  from Non-Volatile Data Storage Devices  106 . In some embodiments, for example, the Virtual Resource Properties  132  may include an indication of whether Virtual Resources  112  are allocated from non-volatile data storage devices that provide data redundancy (RAID) protection. In such embodiments, Virtual Resource Properties  132  may include an indication that Virtual Resources  112  are allocated from non-volatile data storage devices that do not provide data redundancy protection, e.g. an indication that Non-Volatile Data Storage Devices  106  do not provide data redundancy protection. In response to an indication in Virtual Resource Properties  132  that Virtual Resources  112  are allocated from non-volatile data storage devices that do not provide data redundancy protection, Configuration Logic  124  may configure I/O Request Processing Stack  126  such that I/O Request Processing Stack  126  includes and/or executes program logic that provides data redundancy protection (e.g. RAID protection) for data indicated by write requests in I/O Requests  152  that are processed by Virtual SP- 1   116 . Similarly, in response to an indication in Virtual Resource Properties  132  that Virtual Resources  112  are allocated from non-volatile data storage devices that do not provide data redundancy protection, Configuration Logic  138  may configure I/O Request Processing Stack  140  such that I/O Request Processing Stack  140  includes and/or executes program logic that provides data redundancy protection (e.g. RAID protection) for data indicated by write requests in I/O Requests  152  that are processed by Virtual SP- 2   118 . 
     In another example, Virtual Resource Properties  132  may include an indication that Virtual Resources  112  are allocated from non-volatile data storage devices that do provide data redundancy protection, e.g. an indication that Non-Volatile Data Storage Devices  106  do provide data redundancy protection. In response to an indication in Virtual Resource Properties  132  that Virtual Resources  112  are allocated from non-volatile data storage devices that do provide data redundancy protection, Configuration Logic  124  may configure I/O Request Processing Stack  126  such that I/O Request Processing Stack  126  does not include or execute program logic that provides data redundancy protection (e.g. RAID protection) for data indicated by write requests in I/O Requests  152  that are processed by Virtual SP- 1   116 . Similarly, in response to an indication in Virtual Resource Properties  132  that Virtual Resources  112  are allocated from non-volatile data storage devices that do provide data redundancy protection, Configuration Logic  138  may configure I/O Request Processing Stack  140  such that I/O Request Processing Stack  140  does not include or execute program logic that provides data redundancy protection (e.g. RAID protection) for data indicated by write requests in I/O Requests  152  that are processed by Virtual SP- 2   118 . 
     While the preceding examples were with regard to use cases in which the disclosed technology detects whether Non-Volatile Data Storage Devices  106  either provide or do not provide a data redundancy protection data service, and in which the disclosed technology configures the I/O request processing stacks in Virtual SP- 1   116  and Virtual SP- 2   118  accordingly, the disclose technology may alternatively, or in addition, be embodied to operate in response to indications in Virtual Resource Properties  132  as to whether Virtual Resources  112  are allocated from non-volatile data storage devices that provide other data services, e.g. data deduplication, data compression, and/or data encryption. Accordingly, in some embodiments, configuration logic in Virtual SP- 1   116  and/or Virtual SP- 2   118  may operate responsive to an indication in Virtual Resource Properties  132  that Non-Volatile Data Storage Devices  106  do not provide data deduplication, data compression, and/or data encryption, by configuring the I/O request processing stack (e.g. I/O Request Processing Stack  126  and/or I/O Request Processing Stack  140 ) to include and/or execute program logic that provides that data service or data services that are not provided by Non-Volatile Data Storage Devices  106  for data indicated by write requests in I/O Requests  152  that are processed by the respective one of Virtual SP- 1   116  and/or Virtual SP- 2   118 . In such embodiments, configuration logic in Virtual SP- 1   116  and/or Virtual SP- 2   118  may operate responsive to an indication in Virtual Resource Properties  132  that Non-Volatile Data Storage Devices  106  do provide data deduplication, data compression, or data encryption, by configuring the I/O request processing stack (e.g. I/O Request Processing Stack  126  and/or I/O Request Processing Stack  140 ) to not include or execute program logic that provides the data service or data services that are provided by Non-Volatile Data Storage Devices  106  for data indicated by write requests in I/O Requests  152  that are processed by the respective one of Virtual SP- 1   116  and/or Virtual SP- 2   118 . 
       FIG. 2  is a block diagram showing a first example of automatically configuring an I/O request processing stack of a virtual storage processor in response to properties of virtual resources that are provided to and consumed by multiple virtual storage processors in a virtual storage appliance while processing I/O requests received from at least one application. Virtual Resources Properties  200  is an example of Virtual Resources Properties  132 , and I/O Request Processing Stack  206  is an example of I/O Request Processing Stack  126  and/or I/O Request Processing Stack  140  shown in  FIG. 1 . I/O Request Processing Stack  206  provides an execution path for at least a portion of the processing of I/O Requests  150 . Those skilled in the art will recognize that the I/O Request Processing Stack  206  shown in  FIG. 2  is simplified for purposes of concise explanation and clear illustration of the disclosed system, and that various components and/or elements other than those shown in and described with reference to  FIG. 2  may also be present in the I/O Request Processing Stack  206 . In some embodiments, processing of individual I/O requests by layers within the I/O Request Processing Stack  206  may begin at the top of the I/O Request Processing Stack  206  and propagate downwards. 
     As shown in the example of  FIG. 2 , Virtual Resources Properties  200  may include indications that the underlying physical non-volatile data storage devices from which are allocated one or more virtual resources that are provided to the multiple virtual storage processors do not provide one or more specific data services, e.g. do not provide RAID data redundancy protection. For example, in response to an Indication  202  that the underlying physical non-volatile data storage devices do not provide data redundancy protection, a configuration of the virtual storage processors is performed at  204 , e.g. by Configuration Logic  124  and/or Configuration Logic  138 . In response to the Indication  202 , the virtual storage processor configuration performed at  204  results in the I/O Request Processing Stack  206  being configured to include and/or cause to be executed program logic that provides RAID data redundancy protection with regard to the data indicated by I/O Requests  152  (e.g. data indicated by write requests in I/O Requests  152 ), as illustrated in  FIG. 2  by the presence of RAID Protection Layer  212  in the I/O Request Processing Stack  206  resulting from Virtual Storage Processor Configuration  204 . 
     As also shown in  FIG. 2 , I/O Request Processing Stack  206  may include and/or cause to be executed a Replicated Cache Layer  208  containing program logic that operates by storing identical data across copies of a replicated cache that are located within each of the multiple virtual storage processors, as described above with reference to  FIG. 1 . I/O Request Processing Stack  206  may also include some number of other Non-Redundant Layers  210 . For example, Non-Redundant Layers  210  may include and/or cause to be executed one or more layers of program logic that provide one or more other data services that are also not provided by the underlying non-volatile data storage devices. For example, Virtual Resources Properties  200  may also include an indication or indications that the underlying non-volatile data storage devices do not provide one or more data services other than data redundancy protection, such as data deduplication, data compression, and/or data encryption. The configuration performed at  204  may accordingly also result in Non-Redundant Layers  210  being included in I/O Request Processing Stack  206 , which may include and/or cause to be executed one or more layers of program logic that, when executed, provide one or more other specific data services that are performed on data that is indicated by and/or contained in write requests within I/O Requests  152 , e.g. layers that provide specific data services that Virtual Resources Properties  200  also indicated are not provided by the underlying non-volatile data storage devices. In addition, examples of other layers of program logic that in some embodiments may also be included in and/or caused to be executed by I/O Request Processing Stack  206  may include a storage pool layer that manages the allocation of units of non-volatile data storage from Virtual Resources  112  to storage objects, and a mapping layer that maps individual storage objects to specific portions of the Virtual Resources  112  that are allocated from the storage pool to the storage objects. 
       FIG. 3  is a block diagram showing a second example of automatically configuring an I/O request processing stack in a virtual storage processor in response to properties of virtual resources that are provided to and consumed by multiple virtual storage processors in a virtual storage appliance while processing I/O requests received from at least one application. Virtual Resources Properties  300  is a second example of Virtual Resources Properties  132 , and I/O Request Processing Stack  306  is a second example of I/O Request Processing Stack  126  and/or I/O Request Processing Stack  140  shown in  FIG. 1 . As shown in the example of  FIG. 3 , Virtual Resources Properties  300  may include indications that the underlying physical non-volatile data storage devices from which are allocated one or more virtual resources that are provided to the multiple virtual storage processors do provide one or more specific data services, e.g. an indication that the underlying physical non-volatile data storage devices do provide RAID data redundancy protection. For example, in response to an Indication  302  that the underlying physical non-volatile data storage devices do provide data redundancy protection, a configuration of the virtual storage processors may be performed at  304 , e.g. by Configuration Logic  124  and/or Configuration Logic  138 . In response to the Indication  302 , the virtual storage processor configuration performed at  304  results in the I/O Request Processing Stack  306  being configured to not include and/or cause to be executed program logic that provides RAID data redundancy protection with regard to data indicated by I/O Requests  152 , as illustrated in  FIG. 3  by the lack of any RAID protection layer in I/O Request Processing Stack  306 . Similar to I/O Request Processing Stack  206  shown in  FIG. 2 , I/O Request Processing Stack  306  may include and/or cause to be executed a Replicated Cache Layer  308  of program logic that operates by storing identical data across copies of a replicated cache that are located within each of the multiple virtual storage processors as described above. Also similar to I/O Request Processing Stack  206 , I/O Request Processing Stack  306  may also include some number of Non-Redundant Layers  310 , to provide one or more other data services that are not provided by the underlying non-volatile data storage devices, and/or other layers of program logic such as a storage pool layer that manages the allocation of units of non-volatile data storage from Virtual Resources  112  to storage objects, and a mapping layer that maps individual storage objects to specific portions of the Virtual Resources  112  that are allocated from the storage pool to the storage objects. 
       FIG. 4  is a flow chart showing an example of steps that may be performed in some embodiments. At step  400 , a virtual storage appliance having multiple virtual storage resources is installed in a virtualized execution environment, e.g. the virtual storage appliance is booted up in the virtualized execution environment. Each one of the virtual storage processors executes as a virtual machine in the virtualized execution environment. 
     At step  402 , at the time the virtual storage appliance is installed, properties of virtual resources provided by the virtualized execution environment to the virtual storage processors are obtained. The virtual resources are subsequently consumed by the virtual storage processors while the virtual storage processors process Input/Output (I/O) requests received from at least one application. 
     At step  404 , the virtual storage processors are automatically configured in response to the properties of the virtual resources provided by the virtualized execution environment. 
     As will be appreciated by those skilled in the art, the technologies disclosed herein may be embodied as a system, method or computer program product. Accordingly, each specific feature of the present disclosure may be embodied using hardware, software (including firmware, resident software, micro-code, etc.) or a combination of software and hardware. Furthermore, the technologies disclosed herein may take the form of a computer program product embodied in one or more non-transitory computer readable storage medium(s) having computer readable program code stored thereon for causing a processor and/or computer system to perform the techniques of the present disclosure. 
     Any combination of one or more computer readable storage medium(s) may be utilized. The computer readable storage medium may be, for example, but not limited to, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any non-transitory tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     The figures include block diagram and flowchart illustrations of methods, apparatus(s) and computer program products according to one or more embodiments of the invention. It will be understood that each block in such figures, and combinations of these blocks, can be implemented by computer program instructions. These computer program instructions may be executed on processing circuitry to form specialized hardware. These computer program instructions may further be loaded onto a computer or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the block or blocks. These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the block or blocks. 
     Those skilled in the art will readily appreciate that programs defining the functions of the present invention can be delivered to a computer in many forms; including, but not limited to: (a) information permanently stored on non-writable storage media (e.g. read only memory devices within a computer such as ROM or CD-ROM disks readable by a computer I/O attachment); or (b) information alterably stored on writable storage media. 
     While the invention is described through the above exemplary embodiments, it will be understood by those of ordinary skill in the art that modification to and variation of the illustrated embodiments may be made without departing from the inventive concepts herein disclosed.