Hi Pablo,

The 'ls' is probably getting stuck because the I/O is very slow and file system 
metadata writes are stuck in the I/O
queue while locks are held on the file system metadata pending the completion of those 
writes.

The problem could be that you are saturating the cache allocations for the EMC LUNs 
containing your archive destination
file system. See the answer at http://www.ixora.com.au/q+a/0010/20102738.htm for a bit 
about the EMC cache allocation
policy. To solve the problem you can use LVM to stripe a large number of small LUNs 
together so as to increase the total
amount of cache available for the archival writes. You would also do well to avoid 
RAID-S of course!

@   Regards,
@   Steve Adams
@   http://www.ixora.com.au/              -  For DBAs
@   http://www.christianity.net.au/       -  For all



-----Original Message-----
Sent: Thursday, 1 November 2001 5:45
To: Multiple recipients of list ORACLE-L


Hi list,

  Oracle 7.3.4
  HP-UX
  log_archive_buffer_size=32 (redo log blocks = 1K)
  log_archive_buffers=4
  Filesystem based (no direct I/O)

  I've been detecting that my box gets stucked
eventually for some time.
  When this happens I can't do even a "ls" (it
actually executes it but it takes a long time).
  If I check my cpu with TOP, I see 47% idle time and
there's no process monopolizing the CPU.
  But when I check disk activity with sar -d I see
that  one disk is 100% busy and it's avwait+avserv >
1000 ms. The other disks are fine.
  I then check disk activity with Glance and I can
identify the process that's writting/reading on this
disk is: ARCH (ARCH is writting a 1.9 GB redo log.)

  So here are my doubts:
      1)If only one disk is saturated (I've got about
30 disks in this box (a SYMMETRIX array) with some
controllers), why does the whole box get stucked? why
are even other applications connected to other
instances running on this box affected? (may be
because the HP-UX LVM system gets saturated???)

     2) What can I do to avoid this problem?, (reduce
log_archive_buffers parameter may be, or increase
log_archive_buffer_size)

help me on this
Thanks

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Author: Steve Adams
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