RE: RMAN Performance Maladies

  • From: "Herring Dave - dherri" <Dave.Herring@xxxxxxxxxx>
  • To: <MFontana@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Mon, 12 Feb 2007 12:10:40 -0600

Here's some average stats for our hot backups with 6 channels configured
and filesperset at 6 as well, using Legato with RMAN:

BACKUP_TYPE AVG_BACKUP_MINUTES AVG_GB_BACKED_UP AVG_XFER_RATE_MB_PER_SEC
----------- ------------------ ---------------- ------------------------
D                       502.35         2,790.66                    27.92
I                       156.44           280.40                     6.43
L                        31.79            84.80                    26.85

We have a full done weekly, incremental 6 days a week, and archive-only
every day at 7am.

No tuning done but then again not a lot is available to tune.

HTH.

Dave

___________________________________

David C. Herring, DBA  |   A c x i o m  D e l i v e r y  C e n t e r  O
r g a n i z a t i o n

630-944-4762 office | 630-430-5988 wireless | 630-944-4989 fax


> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]
> On Behalf Of Michael Fontana
> Sent: Monday, February 12, 2007 10:15 AM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: RMAN Performance Maladies
> 
> 
> 
> We have just implemented RMAN against our largest Siebel
implementation
> (don't laugh - but it's less then 1/2 terrabyte).
> We did so because now that we have upgraded to Oracle 10gR2 (10.2.0.2)
> we can take advantage of flash recovery features and full backup
> compression similar to which we achived with our old backup product
(BMC
> Sqlbacktrack).  We customarily take full backups nightly, as per our
> SLA, and at this point, incrementals are not an option.  However, the
> actual runtime to complete a full database backup with RMAN compared
to
> SqlBackTrack has gone from 30 minutes to over 4 1/2 hours!
> 
> I have seen anecdotal reports of long runtimes for full RMAN backups
on
> this list, but I've seen an overwhelming number of guffaws from the
more
> elite and experienced poster indicating that this must be user error
or
> some other database performance problem that any competent DBA should
> easily be able to solve without posting to this list.  However, even
> after opening an SR with Oracle support, who seems to believe our
> runtime is in the expected range, we still believe something can be
done
> to overcome the huge IO spike and slow performance we are witnessing
> during the backup, and we are not that experienced with RMAN from a
> performance and tuning perspective, and would appreciated anyone's
> insights or experiences.
> 
> My question is - has anyone actually run RMAN against a large (> 200g)
> database right out of the box without tuning?
> 
> Has anyone spent a great deal of time tuning?
> 
> We are running 4 channels, have an 8 cpu Sunsparc solaris with 16g of
> memory, and have experimented with recommended parameter settings for
> maxsetsize and maxfilesperset without success.  Any information or
> assistance or comment would be appreciated, thanks in advance!
> 
> --
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