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Storage has always been one of the major problems with virtualization in the data center. All the storage systems (NFS, Fibre Channel, iSCSI, FC over Ethernet) currently used by VMware's vSphere were invented before x86 virtualization became a factor and were designed to present a single storage object (LUN or volume) to a single server.
Virtualization changed that. No longer do we have a 1:1 relationship with servers and storage; we have a many-to-one relationship. With this in mind, VMware designed vSphere Virtual Volumes (VVOLs) with three broad goals:
- Simplify storage operation;
- Provide granular delivery of storage capabilities; and
- Increase the utilization of storage arrays.
VSphere VVOLs simplify storage by making the storage administrator responsible only for the provisioning of a single large pool of storage from a storage array and presenting it -- and the capabilities they would like surfaced up from it (performance, data protection, encryption and so on) -- to vSphere for consumption. Using vSphere Virtual Volumes, the virtual admin can self-provision a pool of storage as needed. When creating a virtual machine (VM), a virtual admin can also assign the VM any of the capabilities the array possesses.
Since it would be extremely time consuming for the virtual admin to manually select each capability the VM should possess, this is where Storage Policy Based Management (SBPM) comes into play. With SPBM, a policy is created from the set of capabilities surfaced up from the array and then used to assign a VM to storage with the desired capabilities.
To increase the utilization of storage arrays, VMware has offloaded data-related tasks such as snapshots, cloning, replication or quality of service directly to the array. Most current arrays can perform these tasks almost instantaneously. This also frees the server to pursue virtualization tasks rather than these storage-related tasks.
In the end, vSphere Virtual Volumes improvements allow storage to become VM-centric rather than LUN- or volume-centric.
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Dig Deeper on Storage for virtual environments
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