Comments below.
HJR
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Resources for Oracle: http://www.hjrdba.com
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"Scott" <segruber_at_bellsouth.net> wrote in message
news:34e19c10.0202061402.4bd6a7e8_at_posting.google.com...
> The site where I work is looking into RMAN as a future possibility.
> What I need to know from the DBAs out there is are you using RMAN ? If
> so why and what is it's biggest plus? Any drawbacks ?
>
Two big plusses: first, it does hot backups without putting enormous strain
on your redo sub-system. O/S hot backups require an entire block to be
logged the first time a transaction hits it, regardless of how pathetically
small the transaction is. RMAN doesn't. Second, because it's an Oracle
utility that understands Oracle block structure, RMAN will detect corruption
during a backup (and bomb out... which isn't so hot, but at least you know
there's a problem). With an O/S backup, any corruption in the file goes
along for the copy, and you'll not know about it until either it's too late
or you remember to run dbv.
Also (OK, three or more big pluses!): understanding Oracle blocks, RMAN is
capable of skipping empty ones. O/S backups are a byte-for-byte copy,
regardless of how useless a particular byte might be. RMAN backs up only
what needs backing up -therefore, the backup sets are smaller, and faster to
produce.
Then again, you can do incremental/cumulative RMAN backups. No such concept
with O/S backups, of course. Incremental backups are smaller again than any
O/S backup you are ever going to perform.
Drawbacks? A scripting language from hell. So much rope (ie, flexibility)
you can hang yourself. The need for a catalog database.
Good News: there are no more drawbacks in 9i's version of RMAN. No need for
a catalog, and a scripting language that reads 'backup database;'.
With 9i, I can't think of a single reason (except sheer conservatism or
bloody-mindedness) why anybody would *not* want to use RMAN. The days of
O/S backups are over, I think. Indeed, it wouldn't surprise me if, in a few
versions' time, Oracle announced that they would henceforth no longer
support the taking of O/S backups. The push is already clearly on to get
customers using RMAN, after all...
Regards
HJR
> If you're not using RMAN, why not ? Is it based on any drawbacks ?
>
> And Have you had any problems with RMAN that could not be addressed
> and fixed ?
>
> How many of the past companies you worked for used RMAN ? And how many
> companies you worked for did not use RMAN ?
>
>
> Please send all replies to : gruber_at_mac.com, I'm trying to come up
> with a business case for RMAN. Thanks for all your input in advance,
>
> Scott Gruber
> Senior UNIX Systems Administrator
>
> ( Even though I'm a Systems administrator I have used RMAN in the past
> and I think it is a great backup/recovery tool )
Received on Thu Feb 07 2002 - 01:49:21 CST
