6.7

Table Of Contents
If your environment uses LUN IDs that are greater than 1023, change the number of scanned LUNs
through the Disk.MaxLUN parameter. See Change the Number of Scanned Storage Devices.
Best Practices for vSphere Virtual Volumes Performance
To ensure optimal vSphere Virtual Volumes performance results, follow these recommendations.
Using Dierent VM Storage Policies for Individual Virtual Volumes
By default, all components of a virtual machine in the Virtual Volumes 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 vSphere Client, you cannot change the VM storage policy assignment for swap-VVol,
memory-VVol, or snapshot-VVol.
See Create a VM Storage Policy for Virtual Volumes.
Getting a Host Profile with Virtual Volumes
The best way to get a host profile with Virtual Volumes 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
n
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.
n
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 Volumes.
Suppose that your VM has two virtual disks, and you take two snapshots with memory. Your VM might
occupy up to 10 VVol objects: a config-VVol, a swap-VVol, two data-VVols, four snapshot-VVols, and two
memory snapshot-VVols.
vSphere Storage
VMware, Inc. 297