Thanks to all the folks who have responded on this question. We have made
progress, and I wanted to comment on it, and ask another question.
Our problem appears to have been *largely* a hardware problem. Our oracle
distribution is on a 2-disk mirror on the swxcr. We began by seeing atrocious
performance when loading databases onto logical (mirrored) volumes. We then
observed that if you did a disk-to-disk copy across logical volumes, while
you tried to do anything in oracle, I/O across the swxcr would occur for
about 2 seconds at a time, with 6-8 second periods where the system was
idle and no I/O occurred. No hardware errors have ever been logged, nor
log entries. We were, however, able to do either:
* multiple copies disk-to-disk across swxcr when oracle was inactive
or
* oracle operations when no copies occurred.
We worked extensively with DEC's software support, in particular
their Oracle expert, on this, they did some tuning, we did some tuning,
and saw some improvement, but the problem still occurred in some situations.
There was one oddity, however - the swxcrmgr showed a fair number (60) of
"misc. errors" on one half of the mirror set which contained the oracle
distribution. Today we played with disabling alternate halves of this mirror
set, and doing copies on the remaining disk, and the system crashed twice
when we were doing things on one particular half of the mirror. I swapped
out that disk, rebuilt the mirror onto the replacement disk, and the
system is now running without the I/O lapses.
We are, however, still getting rather low response from our oracle apps, and
are
continuing to work on this with DEC. We have yet to prove that Oracle
7.3.4 performs as well on DU 4.0d as 7.3.3 did on DU 4.0b.
Now for the question. Has anyone had specific problems with a swxcr disk
which displayed "Misc. errors" but which logged no uerf errors? Anyone
have any info about what kinds of things might be included in that "misc.
errors" category that could result in serious problems with the system?
And, lastly, if those "misc. errors" can be serious, why does the system
not log them anywhere else???
TIA...
--
Judith Reed
jreed_at_appliedtheory.com
Received on Fri May 22 1998 - 18:59:01 NZST