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Home -> Community -> Mailing Lists -> Oracle-L -> Re: RMAN Performance Maladies
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On 2/12/07, Michael Fontana <MFontana_at_verio.net> wrote:
>
>
> ...
> 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 am curious as to how your system was backing up 500+ gig in 30 minutes.
Was this due to the compression?
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
Seems reasonable to me.
My question is - has anyone actually run RMAN against a large (> 200g)
> database right out of the box without tuning?
We run 3 channels to a fairly new tape library. I can't recall the type of
drives,
but they are fairly fast. We use Veritas Netbackup.
Backing up a 700G 9i database takes about 3 hours. With our older and slower library, it took about 6 hours.
Has anyone spent a great deal of time tuning?
No, future project though.
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!
You need to determine which you want to maximize, backup performance or restore performance. When dealing with tape, one is always at the expense of the other.
Some things to look at are:
* number of channels
* use incremental (level 1+) backups
* filesperset.
Higher = better backup performance (keep the tape streaming)
better restore performance for entire db restores
Lower = Better Restore performance for single files ( no reading large
archives for 1 file)
See ML Note 388422.1 RMAN best practices
There is also a tuning chapter in the Oracle backup manual.
Don't forget any tuning info for your backup software, the MLM layer that is.
I'm still curious about those 30 minute backup times with SQL Backtrack.
A 500G database going into 4 channels in 30 minutes is 75meg per second.
There must be some very fast compression going on somewhere, or you have some really fast drives.
HTH
-- Jared Still Certifiable Oracle DBA and Part Time Perl Evangelist -- http://www.freelists.org/webpage/oracle-lReceived on Mon Feb 12 2007 - 16:51:59 CST
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