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Re: Oracle on AIX hangs

From: Carel-Jan Engel <>
Date: Thu, 26 Jan 2006 23:30:08 +0100
Message-Id: <>


What kind of filesystem do you use? And what mount options? Do you use direct IO? If not, AIX will inevitably use its filesystem cache. A couple of months ago I was at a site where the LOCK_SGA parameter wasn't set, and no direct IO was used. AIX decided to swap out the SGA, and keep the FS cache in memory.
Can swapping be the cause of the saturation of hdisk0? Can it be that the SGA is swapped? An Oracle login will not be very fast then, to say the least.

Best regards,

Carel-Jan Engel

If you think education is expensive, try ignorance. (Derek Bok) ===

AIX 5.2 seems
On Thu, 2006-01-26 at 13:22 -0700, Allen, Brandon wrote:
> Anyone else seen anything like this?
> Oracle, AIX 5.2 ML7
> Recently migrated to new server, from Oracle 8.1.7 & AIX 5.1, and
> since moving to the new server we've had a few instances of horrible
> performance where hdisk0 is pegged at 100% utilization. When this
> happens it takes 60 seconds just to establish a telnet connection and
> all Oracle sessions, as well as new connection attempts just hang
> indefinitely. We can't even get a "conn / as sysdba" connection so we
> can't get a hanganalyze or systemstate dump.
> After we killed all database server processes (not the background
> processes), the hdisk0 utilization dropped down to zero, but then as
> soon as we try to connect again, the connection attempt hangs and
> hdisk0 goes back to 100%. We can't even shutdown the instance since
> we can't connect so we have to kill it, and then the problem goes away
> and does not come back when the instance is restarted . . . until the
> next time, which may be days or weeks later. We haven't been able to
> identify any pattern to the occurrences yet.
> I've been all over Google and Metalink with no luck.
> Any ideas?
> Thanks,
> Brandon
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Received on Thu Jan 26 2006 - 16:30:08 CST

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