Thanks to replies ...
Corinne Haesaerts
Fletcher Joe
Danny Petterson
alan_at_nabeth.cxo.cpqcorp
we have resolved the I/O problem and now have the full PK4 applied.
The I/O problem was due to multi-volume 'V4' AdvFS file domains. We
backed these up, applied the full PK4 fixes, recreated the file
systems as 'V5' and restored the data. (no I/O error's so far...)
As a result performance has improved but read I/O time is still a slow
18ms (compared with <10ms on 4.0D)
Elapsed job time is now about 30-60% worse than that under 4.0D
It has been suggested ...
"do not use your V4.x /etc/sysconfigtab in V5".
apart from changing 'fifo_do_adaptive = 0' we are running it unchanged
...a review of settings is underway.
The other suggestion is that Oracle is using direct I/O (new with Unix
V5) and that this performs badly.
We attempted to switch this off by setting the ORA_INIT parameter
'DISC_ASYNC_IO' to false. The theory being that Oracle avoids using
direct I/O if it's not allowed to do asynchronous I/O. This did not
affect performance as far as we could tell.
At 8.1.7.2 Oracle have introduced a 'hidden' ORA_INIT parameter which
allows one to explicitly disable Oracle's use of direct I/O.
We are investigating the upgrade (8.1.7.0 to 8.1.7.2) and plan to test
this out.
Summary of original report:
Upgraded from 4.0D to 5.1PK4
Random I/O error when copying a file between file systems.
The problem was 'fixed' by removing 5 patches 653, 494, 232, 230 and
226.
Batch jobs took 2 to 3 times longer than at 4.0D,
due to Read I/O time from the database, previously <10ms now about
26ms. Copying large files between file systems also seemed slower.
Applying the missing patches from PK4 reduced the Read I/O time to
18ms and jobs ran at less than twice the elapsed time of 4.0D
BUT the I/O problem caused jobs which wrote to flat files to fail.
We removed the 5 patches again and changed the kernel parameter
'fifo_do_adaptive = 0' as per a previous summary (Thanks Rob Pieters)
This gave us a 15% improvement in elapsed time but the longer Read I/O
remained (>20ms).
Brian Hunter
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Received on Wed Jan 16 2002 - 15:35:39 NZDT