I am following this doc to see if VAAI is supported on our SAN but copying a 20G vmdk or creating a vmdk does not change the status of hardware acceleration.
It still shows hardware status unknown
As mentioned, ensure that your array is in the HCL that supports VAAI, but also make sure the array has the firmware that supports it. Most arrays will need an upgrade in the firmware to bring turn on this feature. You also want to make sure you're running ESX(i) 4.1 and again, depending on the array vendor, you may need to install packages on the host (e.g. 3par, you need to install 3par VAAI modules before using it).
You should take a look at using esxtop under "u" option and view the VAAI statistics, if they're changing depending on the type of test, then you're making using of the new VAAI SCSI primitives.
From your current message, the host is unable to determine if VAAI is supported. I would verify that you meet all requirements and try again.
VMware vExpert 2009,2010
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