One Extremely Busy Disk

[prumschlag@xxxxxxxxxx]

We have been having an intermittent response time problem lately that always
seems to happen around 7:00 AM.  This is shift change time in the factory, so
there is plenty of activity on the system (in other words, tough to tie the
problem to one user or job).  I have looked at the Ops Nav monitors and one
thing looks out of kilter.  At about this time, one of the disk drives gets very
busy for a short period of time, usually 30 to 60 seconds.  This morning was the
worst I have seen: a full three minutes at 90% busy.  In the four days that I
have watched it, it has always been disk # 21 or 37.  Our journals are in a
separate ASP, not one of these drives.  I know of no jobs that we have setup
that would force a write to the disk for every record update.  That does not
mean we don't have any, it just means I may not know about it.  CPU activity
looks normal during this time frame.  Disk Utilization is around 80% .

Now that I have rambled on, three more specific questions:

   1.  We don't normally watch disk drive activity, because it just usually is
   not a problem so I don't know if this is a normal occurrence or not.  Is this
   a red flag?

   2.  How can I tie the activity on the disk back to a specific job causing the
   activity?

   3.  Could there be some kind of system activity that is forcing a disk
   read/update to the same record?  Is it time to get IBM involved?

We are running J D Edwards World on  a V4R3 model 730, with 48 disk drives (
6607-070's, 072's, and 074's) with RAID active.

Phil Rumschlag


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