Re: DBWR, Direct I/O and the Devil

From: Don Seiler <don_at_seiler.us>
Date: Thu, 29 Nov 2007 08:24:44 -0600
Message-ID: <716f7a630711290624h4d167891i7005e6d8aae59e8e@mail.gmail.com>

I made the change to filesystemio_options=setall, and lowered db_writer_processes=1 (might be unrelated, just providing fyi).

However I'm now getting this error from RMAN when I try to do my archivelog and controlfile backups, which I do every couple of hours.

Starting Control File and SPFILE Autobackup at 29-NOV-07

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================

RMAN-03009: failure of Control File and SPFILE Autobackup command on ORA_DISK_1 channel at 11/29/2007 02:00:46
ORA-19502: write error on file "/rman/c-3171457975-20071129-00", blockno 321 (blocksize=16384)
ORA-27061: waiting for async I/Os failed

Linux-x86_64 Error: 14: Bad address
Additional information: -1
Additional information: 1048576

Here is how my /rman is currently mounted (output from `mount`): /dev/vx/dsk/oracle-01/rman-temp on /rman type vxfs (rw,delaylog,largefiles,mincache=direct,convosync=direct,ioerror=mwdisable)

Here is one of the datafile partitions, they are all the same: /dev/vx/dsk/oracle-01/u22 on /u22 type vxfs (rw,delaylog,largefiles,mincache=direct,convosync=direct,noatime,ioerror=mwdisable)

We are not using ODM with our Veritas.

Don.

On Nov 28, 2007 3:22 PM, Don Seiler <don_at_seiler.us> wrote:
> On Nov 28, 2007 3:07 PM, Bobak, Mark <Mark.Bobak_at_il.proquest.com> wrote:
> > I think you want both direct *and* async I/O configured, if your O/S and filesystem will support it. In that case (with async i/o) you probably will only need 1 DBWR.
>
> Alright so I should set filesystemio_options=setall rather than
> directio? Are there any other parameters to look at?
>
> Don't I still need to mount the disk with "mincache=direct,convosync=direct"?
>
> > http://www.ixora.com.au/tips/avoid_buffered_io.htm
> > http://www.ixora.com.au/tips/use_asynchronous_io.htm
>
> Yep I've been reading this already.
>
> My connotation was that direct I/O the opposite of asynchronous I/O.
> I'm seeing now that they are more or less independent states of I/O
> covering different aspects of behavior.
>
>
> --
> Don Seiler
> http://seilerwerks.wordpress.com
> ultimate: http://www.mufc.us
>

-- 
Don Seiler
http://seilerwerks.wordpress.com
ultimate: http://www.mufc.us
--
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Received on Thu Nov 29 2007 - 08:24:44 CST