Finding a bad path.

Log into the SAN switch, I am assuming it is a Brocade, and run a “porterr show”  and copy/paste the output to a file in case we need to compare it.

Then reset the counters of the 'porterr show' using command “portstats clear”

Now watch the counters of the “porterr show” while testing and/or throughout the day and see which paths start to record errors on them and how fast they happen.

You should be able to narrow down the failing path(s)with the 'porterr show' data then you will need to start troubleshooting the path devices.>  (ServerHBA/ServerSFP/Fiber/SwitchSFP/SwitchASIC)