FC Dyntrk and Fast IO Failure

[Outsyder]

Hi.

We've been running with the same FC configuration for ever...(since we did not know the option existed until today) with the option for dyntrk=no and fc_err_recov=delayed_fail.

Last weekend, we tried to migrate some DS8300 ports from one switch to another and our AIX servers paths would not recover from the move. I was told that the dyntrk=no was my problem. Found some doc and i am almost sure it is my solution. Anyone ever messed around with changing those settings on the FCs? Can it be done live? What are the advantages of chaning the delayed_fail to fast_fail?
Thanks.

 

[bi]

You can't make the changes live unless you are dual pathed. If you are dual pathed, you have to take one path offline, update the fscsi device, put it back online and then do the same with the other path.

We did try dynamic tracking, but the software we are using for our SAN disks (from a well known third party) does not like dynamic tracking. It was throwing dozens of errors a second when we had it turned on and overwhelmed errpt.

We are trying now just using fast_fail.

One caveat: if for any reason you have to delete your fscsi device and then configure the same device again, fast_fail is turned off, which is the default.

AFter all the child devices are deleted and the only things remaining are the fcs and fscsi devices, do this:

chdev -l fscsiX -a fc_err_recov=fast_fail