A major benefit of the vVol architecture is granularity—its ability to configure each virtual volume as required and ensure that the configuration does not change.
Historically, configuring storage with VMware management tools has required GUI plugins. Every storage vendor’s tools were unique—there was no consistency across vendors. Plugins were integrated with the Web Client, but not with vCenter itself, so there was no integration with the SDK or PowerCLI. Moreover, ensuring on-going configuration compliance was not easy, especially in large environments. Assuring compliance with storage policies generally required 3rd party tools.
With vVol data granularity, an array administrator can configure each virtual disk or VM exactly as required. Moreover, with vVols, data granularity is integrated with vCenter in the form of custom storage policies that VMware administrators create and apply to both VMs and individual virtual disks.
Storage policies are VMware administrator-defined collections of storage capabilities. Storage capabilities are array-specific features that can be applied to volumes on the array. When a storage policy is applied, VMware filters out non-compliant storage so that only compliant targets are presented as options for configuring storage for a VM or vVol.
If an array administrator makes a VM or volume non-compliant with a VMware policy, for example by changing its configuration on the array, VMware marks the VM or VMDK non-compliant. A VMware administrator can remediate non-compliant configurations using only VMware management tools; no array access is required.