Re: RMAN backup slows database performance to a crawl

  • From: "David Barbour" <david.barbour1@xxxxxxxxx>
  • To: jkstill@xxxxxxxxx
  • Date: Thu, 10 Jul 2008 17:30:27 -0400

I have a similar problem, but it's a difference between incrementals and
full backups.  When the full backups run, I've limited the size of the
backup set and I don't have a performance issue.  When the incremental
backups run however, the application basically comes to a screaming halt.
We're on AIX 5.3L, Oracle (soon to be upgraded to 10g - thank you),
with cio mounted filesystems.  Finally got the Sys Admins to mount our QA
box without CIO and I'm going to test the incremental backups using both
setall and asynch in the filsystem_io parameter.

On Thu, Jul 10, 2008 at 5:14 PM, Jared Still <jkstill@xxxxxxxxx> wrote:

> On Thu, Jul 10, 2008 at 1:16 PM, Finn Jorgensen <finn.oracledba@xxxxxxxxx>
> wrote:
>> Checking an AWR report I noticed that the "Av Rd(ms)" column of the
>> tablespace IO stat for that tablespace is at 671ms (Yikes!) when the
>> RMAN job is running and a much more normal 3.6ms when it's not.
> How many channels are being used?
> You may want to reduce the # of channels if > 1.
> You can use the 'SET LIMIT' command to slow down RMAN.
> (it's mostly undocumented)
> See "Making RMAN Perform' at
> There's a couple pages on RATE and SET LIMIT
> --
> Jared Still
> Certifiable Oracle DBA and Part Time Perl Evangelist

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