Earlier today I ran across the following errors in my ESXi logs:
Nov 15 08:03:10 esx02 Hostd: [6BA33B90 info 'Vimsvc.ha-eventmgr'] Event 305408 : Lost access to volume 51f7bd04-ace1a4c9-0114-0017a4770000 (LUN23) due to connectivity issues. Recovery attempt is in progress and outcome will be reported shortly.
It would always recover right away within 1 second and since I am on a Active/Active array it was not really an interruption. It did bother me. So I did some research and came up with fillwords.
The process as I understand it is that switches use these fillwords to setup link initialization. Up until firmware 6.1 this was done by sending IDLE/IDLE messages. Both sides would respond with IDLE this was specific to devices running 1G/2G/4G speeds. Brocade then setup new fillword modes as show below:
Mode 0 Use IDLE in link init and IDLE as fill word
Mode 1 Use ARB in link init and ARB as fill word
Mode 2 Use IDLE in link init and ARB as fill word
Mode 3 Try mode 1 first; if it fails then try mode 2
You should set this mode as per your storage and server best practices. I know that for my HP Blades using 8GB virtual connect it is critical to use Mode 3 which I was not using. You can check you current config by logging into the switch and using this command:
And you can switch it via:
portcfgfillword <Port#> <Mode>
You can read a much better written article on that matter here.