Re: RMAN impact

Hmm...  Interesting thought.  Blocks sitting "unread" for long periods of
time.  Of course, that raises the old philosophical question: if a block on
disk becomes corrupt and there is nobody there to read it, will anybody hear
the operations manager's scream?

Personally, I have always held that even with good incrementals, you need to
perform full (level-0) backups relatively frequently.  Except for the very
largest databases, I would think weekly would be the "minimum" frequency --
for something huge (e.g., in the terabyte+ range) I suppose I could maybe
live with monthly.  (IBM added a radical new feature to TSM -- full backups
-- just for people like me, I think.)  One of my reasons for this is to
(help) prevent the backup infrastructure from becoming "oversubscribed".

One of the other nice features of Oracle 10g(R2?) is the ability to recover
individual blocks in the even of corruption.  I've never had occasion to use
it myself [because only Mr. Engel's disks ever fail ;-) ] but it looks good
on paper...

Should you start exporting again?  Nah.  You can do an RMAN "BACKUP VALIDATE
DATABASE" instead.  In fact, with 10g, there is an additional option "CHECK
LOGICAL" that will cause RMAN to crosscheck indexes and tables, which can
detect logical corruption (of the type that occurs when your disk array
loses the contents of its "nonvolatile" write cache) which is otherwise
undetectable by any other means.


On 10/22/06, Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx> wrote: 

 My main concern with CBT is that a block can sit on disk 'unread' for a
long time, depending how often full/level 0 backups are made. And disks
don't fail, except when they're mine.

In the good ol' days we were exporting databases to get blocks checked.
With RMAN, the export became obsolete, because RMAN
would read every block. Now RMAN stops reading every block, should we
start exporting again?

 ...




--
Cheers,
-- Mark Brinsmead
  Staff DBA,
  The Pythian Group
  http://www.pythian.com/blogs

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