To ensure optimal vVols performance results, follow these recommendations.
Using Different VM Storage Policies for Individual Virtual Volume Components
By default, all components of a virtual machine in the vVols environment get a single VM storage policy. However, different components might have different performance characteristics, for example, a database virtual disk and a corresponding log virtual disk. Depending on performance requirements, you can assign different VM storage policies to individual virtual disks and to the VM home file, or config-vVol.
When you use the vSphere Client, you cannot change the VM storage policy assignment for swap-vVol, memory-vVol, or snapshot-vVol.
Getting a Host Profile with vVols
The best way to get a host profile with vVols is to configure a reference host and extract its profile. If you manually edit an existing host profile in the vSphere Client and attach the edited profile to a new host, you might trigger compliance errors. Other unpredictable problems might occur. For more details, see the VMware Knowledge Base article 2146394.
Monitoring I/O Load on Individual Protocol Endpoint
- All virtual volume I/O goes through protocol endpoints (PEs). Arrays select protocol endpoints from several PEs that are accessible to an ESXi host. Arrays can do load balancing and change the binding path that connects the virtual volume and the PE. See Binding and Unbinding Virtual Volumes to Protocol Endpoints.
- On block storage, ESXi gives a large queue depth to I/O because of a potentially high number of virtual volumes. The Scsi.ScsiVVolPESNRO parameter controls the number of I/O that can be queued for PEs. You can configure the parameter on the Advanced System Settings page of the vSphere Client.
Monitoring Array Limitations
A single VM might occupy multiple virtual volumes. See Virtual Volume Objects.
Suppose that your VM has two virtual disks, and you take two snapshots with memory. Your VM might occupy up to 10 vVols objects: a config-vVol, a swap-vVol, two data-vVols, four snapshot-vVols, and two memory snapshot-vVols.
Ensuring that Storage Provider Is Available
- Do not migrate a storage provider VM to vVols storage.
- Back up your storage provider VM.
- When appropriate, use vSphere HA or Site Recovery Manager to protect the storage provider VM.