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How to find out what VAAI supported features your shared storage has in ESXi 5

Recently during the building of my new home lab I have been experimenting with different free storage providers such as FreeNAS, Nexenta, OpenFiler and was pleased to see in the vSphere Client that in some cases it reported that Hardware Acceleration (VAAI) was supported. I performed a few tests to see if it was indeed working and the results were inconclusive as some test were successful and overs were not.

After some Googling I found the command I needed to run in order to find out what VAAI features were supported by my storage providers.

Note: The following command is for ESXi 5. For ESXi 4 commands have a look at the VMware KB1021976

  1. You will first need to enable SSH on your host and connect to it via putty or with a SSH terminal of your choice.
  2. Once logged in run the following command
    esxcli storage core device vaai status get
  3. This command will retrieve the VAAI status and present it to you in the following format

As you can see from my output above Hardware Acceleration is only partially supported. It would be nice if VMware could specify from the GUI which VAAI functions are actually supported by the Datastore

The following is a list of the VAAI features

  • Atomic Test & Set (ATS), which is used during creation and locking of files on the VMFS volume
  • Clone Blocks/Full Copy/XCOPY, which is used to copy or migrate data within the same physical array
  • Zero Blocks/Write Same, which is used to zero-out disk regions
  • Block Delete in ESXi 5.x and later hosts, which allows for space to be reclaimed using the SCSI UNMAP feature. For more information on Block Delete/SCSI UNMAP, see Using vmkfstools to reclaim VMFS deleted blocks on thin-provisioned LUNs (2014849)

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2 thoughts on “How to find out what VAAI supported features your shared storage has in ESXi 5

  • Bill Plein says:

    I tried this today using FreeBSD 10, and got slightly different results. I’m going to dig deeper, but I am wondering of the new iSCSI kernel in FreeBSD 10 is missing some features, or if it is dependent on the underlying storage beneath the ZVOL or filesystem backing the iSCSI LUN.

    • Bill Plein says:

      The more I think about it, the FreeBSD iSCSI stack is probably handing most (all?) CDBs to the underlying storage. I bet that the VAAI capabilities are highly dependent on the underlying storage. Thoughts?

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