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Re: Row cache lock tuning

From: Sean M <smckeownNO_at_BACKSIESearthlink.net>
Date: Tue, 19 Mar 2002 03:06:17 GMT
Message-ID: <3C96AB51.D002A5EF@BACKSIESearthlink.net>


Andrew Mobbs wrote:
>
> The particular application isn't running all the time, and the others
> aren't quite so enthusiastic about generating redo. The shortish run
> I made took 1.5 hours and got through 5x30GB log files. I need to do
> a run at least 4 times as long in the next few days, and hope to spend
> less than all day doing it.

Yikes.

> Seriously though, it does worry me how our customer's DBAs could cope with
> backup of some of the redo rates that I see in benchmarks, especially
> given the predicted increases in volume. While it's not quite up to
> 30MB/s yet, it's at least in the same order of magnitude. If anybody's
> got experience of backing up instances that generate a few hundred GB
> per day redo, I'd be interested to hear.

Just as an example: probably our biggest "offender" does between 100 and 300 gigs a day. But we backup four times that amount since we mirror the archives (at the Oracle level) and take 2 copies of each log to tape (one copy stays onsite). The solution is not, how do you say... cheap? Gotta pay to play.  

> I imagine the answer involves giving a lot of money to tape-library
> vendors. With a load of log groups (say 9), have a 6 drive DLT library,
> 30 MB/s / 6 drives => 5MB/s per drive - just about plausible I guess
> given Quantum claim 6MB/s streaming for DLT8000. That's still 86 tapes
> to shuffle through in a day. ...and then there's data file backup.

:) Sounds like fun. Except it might be hard to catch up with that redo stream the day you lose a tape drive. Redundancy is the datacenter credo.

Regards,
Sean Received on Mon Mar 18 2002 - 21:06:17 CST

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