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RE: Raw Vs. File systems, your opinion?

From: Sonja Sehovic <>
Date: Wed, 6 Dec 2000 11:26:43 +0100
Message-Id: <>

we are considering to move from FS on raw devices. It is a misson critical database (8.1.7 on AIX).
We migrated from 8.1.5 because we noticed a memory leak. Oracle told us it is a bug, and that we should go to the 8.1.7. Well, we are not sure that this resolves our problem so this is the one of the reason to change to the raw devices. What do you think? Do you have any suggestions? Which software are you using for backup? Are there OEM for raw devices?
How do you extend your tablespaces (when I add datafile in FS)?


-----Original Message-----

From: []On Behalf Of Mark Teehan Sent: Wednesday, December 06, 2000 1:25 AM To: Multiple recipients of list ORACLE-L Subject: Re: Raw Vs. File systems, your opinion?

Hmmm dont you love a good religious war every now and again. Having administered about six oracle parallel server clusters for over a year now, Ive changed my opinion completely on raw devices - now I prefer them.
It is easier to see file and volume layouts for databases with complex layouts using Veritas Volume manager's (very nifty) gui. I also get considerable peace of mind knowing that there are no database files that can be deleted at the filesystem level : in the past I've had several unix administrators screwing up my databases by overmounting a filesystem, or something similar.
No such problems with raw partitions : you are less likely to get accidental or malicious damage to a critical database if it is raw, imho. Backups are more complex, but generally only larger sites consider raw partitions, and subsequently have purchased an enterprise level backup tool that handles raw partitions as easily as files.

An aside : for sites that use dedicated redo disks, and put two or three redo log files on each dedicated disk pair : is there any reason not to create more redo groups (say 10) on the same two disk pairs, so that online recovery, if it is required, is less likely to need archive logs to be pulled from tape? It is a better use of the redo pairs than having an online archive log bucket filesystem. Since redo log files are not hot-backedup their total size doesnt matter. Comments?

Perth, Australia


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Author: Mark Teehan

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