Paul Bijnens wrote:

Mike Delaney wrote:

On Fri, Mar 04, 2005 at 06:07:19PM +0100, Paul Bijnens wrote:

Last time I looked at doing backups of Oracle (Ora 6-7-8), I
approached it as follows:  first set each tablespace in hot backup mode
(alter tablespace TS begin backup) then doing a filesystem backup
of all the directories with datafiles, using plain amanda DLE's,
then setting each tablespace out of hot backup mode, (alter
tablespace TS end backup);  then force a redo log switch (alter
system switch logfile) and then doing a backup of the archived redologs.

Ouch.  If that database is seeing any signifigant activity during the
backup, you're going to be generating *alot* of redo with that approach.
Putting the whole database in backup mode at once is typically frowned
upon unless you're using something like mirror splitting or snapshots
so you can turn backup mode off after a few seconds.

That's why you do it during the night...

And on Solaris I do use snapshots, which takes indeed a few seconds
only, for all the DLE's, not only the oracle datafiles.
Never "File changed while reading" messages anymore.

A pitty snapshots on Linux LVM2 does not work (yet).  On some
older systems still running a 2.4.18 kernel and LVM1, I use snapshots
too (and MySQL instead of Oracle: a magnitude or two less in footprint,
and still suitable for the tasks I need.)

/Andreas