I have a customer who has purchased a VNX 7500 array with the intention of moving a bunch of ESXi hosts (4.x I believe at this stage) off of HP EVA 8000 arrays.
One of the questions that came up during initial discussions was “what EMC’s recommended setting was for Disk.DiskMaxIOSize setting in ESX”?.
We were told that HP have a recommendation (which I discovered was 128KB and supported by documentation) but I’ve found nothing that speaks to non-HP equipment.
What I’m looking for is if EMC have any recommendations that speak to modifying the value from default. I understand it’s a tunable parameter and that in one sense it’s best to leave these alone unless there is a need to change them, but that in another sense tuning and measuring may be an approach.
This has come up before on the vSpecialist list, and it was decided that HP had this because of a limitation in the EVA arrays.
VNX has no such limit, and so we recommend leaving it at VMware's default,
is that limitation mentioned on the EVA side relates/equivalent to 'write aside size` or `prefetch disabled size` on the clariiion side?