unix filesystem writes slow over time to xp128 port

[ecorban]

Hi
I started seeing the performance drop on xp128 port for 60mb per sec to 15 mb on an xp128 port. the hpux 11.11 host is performing writes to the luns but slows to a halt after a few (5+ hrs of coninuous write to the lun group. how can i keep the performance high enough on an xp128 array with open 3 luns ? cant seem to increase it at all, any information or docs are appreciated.