Qlogic HBA's, typically found in Dell R720s need the following settings:

Queue Depth of 255 Port Down (timeout?) of 60 Seconds Login Retry Count of 60 Link Down timeout of 30

To see the current HBA settings, ssh into each host and type:

/usr/lib/vmware/vmkmgmt_keyval/vmkmgmt_keyval -a

You cannot set these settings under the Qlogic BIOS. Instead from each SSH session, enter the following:

esxcli system module parameters set -m qlnativefc -p "ql2xmaxqdepth=255 ql2xloginretrycount=60 qlport_down_retry=60"

Reboot, then rerun the first command to see if the settings took. You can also type in esxtop, then hit 'u' and look at the DQLEN field for the various disks.

Sources: [vmware] (http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1002413)

[vmware] (http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1267)

[vmware] (http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=10272016)

- Tim Vruwink