Choosing the storage array for VMware, except base compatibility, which can be checked in VMware Compatibility Guide (Storage/SAN), is also useful to understand is storage system VAAI capable or not.
VAAI (vStorage APIs for Array Integration) is a feature in ESX/ESXi 4.1 and later versions that provides hardware acceleration functionality. It enables your host to offload specific virtual machine and storage management operations to compliant storage hardware. With the storage hardware assistance, your host performs these operations faster and consumes less CPU, memory, and storage fabric bandwidth.
Now VAAI includes the following primitives:
- Blocks Zero is a communication method for thin provisioning capable storage arrays, allowing them to quickly zero out storage capacity for later reclamation.
- Full Copy commands the storage array to make a mirror or snapshot of data without any I/O on the server hardware.
- Hardware Assisted Locking enables more granular control of shared storage resources in ESX clusters.
- Thin Provisioning allows an ESXi to tell the storage array that space that was occupied by a VM (whether it is deleted or migrated to another datastore) can be reclaimed. This allows an array to correctly report space consumption of a Thin Provisioned datastore, and allows customer to correctly monitor and correctly forecast new storage requirements.
Using VAAI can make significantly easier the VMware storage resources administration. The Full Copy primitive is very important when frequent VMs or datastores snapshots are required (usually to provide low RPO value).
And don’t forget to check the availability of VMware plugin for storage system administration.
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