I have an IBM san connected to QLogic HBA.
I'm running OES SP1 (SLES9SP2)
I don't use multipath

when accessing the SAN, with partition like reiserfs, there is some lag.
if I browse the partition (cd /mnt/mountpoint) then do ls
or press tab into bash to completetion, it can takes up to 5-7 seconds
just to list 1 or 2 directories... then partition is managed under EVMS,
and the volume size doesn't matter.
Any clue ?