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RE: Server-managed vs storage-managed backup/recovery?

From: Hand, Michael T <>
Date: Mon, 28 Jun 2004 16:01:47 -0400
Message-ID: <>


John hit all of the major points for the hot-backup via mirror split justification. The one additional use we put to ours is a daily Dbverify. We started this process with an 8.0 database and I wasn't ready to trust RMAN at that point. It will be interesting to see how these two concepts integrate.


-----Original Message-----
From: Tim Gorman [] Sent: Monday, June 28, 2004 3:17 PM
Subject: Re: Server-managed vs storage-managed backup/recovery?

Thanks so much for the reply!

I'm trying to find the middle-ground between RMAN and the mirror-split methods. Right now, my approach is to make use of the CATALOG command to register a mirror-split as a DATAFILECOPY and then back the DATAFILECOPY off to tape using the BACKUP DATAFILECOPY command. This would allow RMAN to check for corrupted blocks, thus achieving the best of both worlds, but I've got a lot of testing to do, and I was wondering if anyone had used this already?



on 6/24/04 3:37 PM, John Kanagaraj at wrote:

> Tim,
> We use the the 'split mirror' hot-backup for our large Apps database. The
> main reasons are (a) Keep backup I/O off the 'live' copy (b) Keep a copy
> the Database 'on-disk' for immediate recovery should a disk disaster strike
> on the live copy. (c) We don't have to really bother about the backup window
> as long as one cycle doesn't step into the next. (d) Clones are simply a
> matter of FTP and archive log application. [Of course, storage $$ isn't an
> issue here, if you know what I mean!]
> Hth,
> John Kanagaraj <><
> DB Soft Inc
> Phone: 408-970-7002 (W)
> Listen to great, commercial-free christian music 24x7x365 at

>> -----Original Message-----
>> From:
>> [] On Behalf Of
>> Sent: Thursday, June 24, 2004 9:02 AM
>> To:
>> Subject: Server-managed vs storage-managed backup/recovery?
>> All,
>> I see a lot of IT shops opting for using the various
>> ?mirror-split? technologies for performing database backups,
>> as opposed to using tape-management software (i.e. Veritas,
>> Legato, Tivoli, etc) or RMAN. To make a long story short, I
>> see this as IT management endorsing the concept of
>> storage-managed storage as opposed to the concept of
>> server-managed storage. Not a bad solution, makes a lot of
>> sense in a lot of ways. Lots of good arguments in favor of
>> storage-managed storage, as long as the services on the server
>> are simple. However, as the existence of this list attests,
>> database-based applications tend to be complex and laden with options.
>> I tend to believe that there is more to the recoverabilt than
>> simply getting the data to tape (or from tape) as quickly as
>> possible, namely:
>> - partial database recoveries
>> - point-in-time recoveries
>> - not backing up READ ONLY tablespaces as frequently as READ
>> WRITE tablespaces
>> - detecting corruption in datafiles and archived redo log files
>> - validating backups, validating restores, validating recoverability
>> - verifying recoverability
>> - reporting and analysis on backup and restore performance
>> All of these are things that RMAN does, but ?mirror-split?
>> techniques make difficult. Still, for shops that have bought
>> into one or more of the various ?mirror-split? options, I find
>> it difficult to try to argue them away from it. At least, the
>> arguments are difficult until serious recovery problems have
>> occurred and the huge range of options offered by Oracle have
>> been constrained by the use of ?mirror-split? backups.
>> So, in the spirit of ?join them rather than beat them?, has
>> anyone managed to combine RMAN with ?split-pair? techniques
>> (i.e. EMC ?TimeFinder? and BCVs, Veritas ?FlashSnap?, Hitachi
>> pair-splits, etc)?
>> I?ve thought about using the RMAN ?catalog? command to add
>> DATAFILECOPYs to the catalog following a ?mirror-split?, but
>> RMAN then tends to try to read those splits during restore
>> operations. Also, the fact of having created a DATAFILECOPY
>> using a mirror split means that RMAN has not been able to
>> check the file for corrupted blocks, an important piece of
>> functionality to lose.
>> I?m also aware of the PROXY operations in RMAN but have not
>> used them. Anyone know if this functionality integrates into
>> the ?mirror-split? techniques?
>> Thanks in advance for any and all information!
>> -Tim

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Received on Mon Jun 28 2004 - 15:00:52 CDT

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