PowerPath/SQL Server/Windows 2003-64bit and EMULEX Queue Depth

I would say that they are wrong because the HBA settings are going to be specific to your storage infrastructure and Microsoft may not be aware of the optimal settings for an Emulex HBA on your storage network connected to EMC arrays. Changing the HBA settings to something other than what is supported by EMC can have a negative impact on the host performance.

Have you seen the "EMC Host Connectivity with Emulex Fibre Channel Host Bus Adapters (HBAs) and Converged Network Adapters (CNAs) in the Windows Environment" document? Start on page 154, it describes the supported settings for the Emulex HBAs in a EMC storage environment.

https://powerlink.emc.com/nsepn/webapps/btg548664833igtcuup4826/km/live1/en_US/Offering_Technical/Technical_Documentation/300-001-157.pdf?mtcs=ZXZlbnRUeXBlPUttQ2xpY2tTZWFyY2hSZXN1bHRzRXZlbnQsZG9jdW1lbnRJZD0wOTAxNDA2NjgwNDNhZTg2LGRhdGFTb3VyY2U9RENUTV9lbl9VU18w

Yes, I have reviewed this doc. All it claims is what the setting is, it doesn't state anything about it being the only setting that will be supported, nor does it explain in detail its implications of DMX LUNs and PowerPath buffering.

You should never change any driver settings unless directed to do so by EMC tech support. the Driver parameters for emulex storport driver at testing, certified, verified, etc.. by EMC engineering ELAB. so without direct guidance from EMC Engineering you should never change or modify driver parameters.

The major reason you can give to your DBAs and management is this:

Without an RPQ, EMC will not support any issues that come up on the host(s) attached to the SAN with non-standard settings. If you run into performance issues and open a ticket, once it's determined that the HBA settings have been modified beyond the norm the SAC will immediately suggest you reset those changes to the EMC recommended changes and will go no further in investigations until you do so.

I've run into similar issues in the past with 'non-standard settings'. Be careful.

Changing an HBA setting does not require an RPQ.

If there are issues after deviating from the EMC-recommended config, and EMC support are engaged, either (a) the host will need to go back to the EMC-recommended config, or (b) an RPQ will be required for support/escalation.

It all comes down to what's more important - knowing that your environment has been tested and is supported by EMC, or forgoing that safety net for a possible performance increase. Or get that RPQ and you'd have the best of both worlds.