Re: Log file I/O throughput

What is your redo size per txn? ('redo size' / 'user commits') from v$osstat What is your avg wait time for 'log file sync'? from v$system_event Do you have any of your tablespaces in 'Hot Backup' mode that generates tonnes of unnecessary redo?

-V

on 10/23/2003 12:58 PM billjohnson said the following:

>Ok - I read through the replies and there seems to be a fair amount of
>discussion regarding hardware. I have heard the same song and dance
>from our UNIX Admin team that the Disk I/O is raid-1, HP Disk, dedicated
>drives....for our redo logs. We are seeing 30% of the DB time in a
>statspack report going to "log file sync" wait. It just jumped through
>the roof from 5% about 1 week ago. I need to find some other
>measurement that will allow me to confirm whether this is a hardware
>issue or a program commit/update issue. When looking at the stats pack
>report, the "user commits" line shows the following:
>
>Statistic Total per Second per
>Trans
>
>--------------------------------- ---------------- ------------ ------------
>
>user commits 92,676 25.7
>1.0
>
>
>
>This number is no different in average commits per second than then the
>system was only spending 5% of the overall time in log file sync wait.
>I need some additional direction on nailing down the real source of the
>problem. This is a 16-way RP-8400 HP-UX 11.i environment running SAP
>4.0B on an Oracle 8.1.7.3 instance. We have about 5,000 users on this
>system. Any ideas? I am a DBA - not a UNIX Admin.
>
>
>--
>Posted via http://dbforums.com
>
>
Received on Thu Oct 23 2003 - 17:53:48 CDT