rman backup to disk, mismatch in amount backed up to each channel
- From: "Hitchman, Peter" <Peter.Hitchman@xxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 22 Oct 2004 13:08:47 +0100
Hi,
We back up an Oracle 8.1.7.4 database to disk using rman. Its about 900 Gb.
It does work, but we find that much more data is getting sent to one channel
than the other. So when its done, one filesystem is over 50% full and the
other is only at 25%. I thought that rman automatically evened out the work
done by each channel and that would result in an even (ish) amount of disk
space being used in each filesystem.
What we want is for the amount written to each channel to be about even,
that way we can do a backup and then rename the directories the backup is in
before we run another one, in case the next backup fails for some reason. We
only two file systems available (and we had to beg for these) and managed to
get enough space in each in theory to hold two disk backups. But its no good
if one of the filesystems goes over 50% with the first backup, because it
means the next one will fail because of lack of disk space.
Does anyone know how we can control rman's behaviour in this case? (By the
way, for reasons that are beyond me, it is not possible to change the disk
space allocation so that the one of the filesystems is 25% bigger that the
other).
Here is the rman script:-
connect target 'xxx/xxx@XXX';
connect catalog 'xxx/xxx@XXX';
run {
allocate channel t1 type disk format '/rman1/backup/cms.%U';
allocate channel t2 type disk format '/rman2/backup/cms.%U';
set limit channel t1 kbytes 10000000;
set limit channel t2 kbytes 10000000;
set command id to 'rman_backup';
backup
incremental level 0 cumulative
skip readonly
skip offline
database;
sql 'alter system archive log current';
change archivelog all crosscheck;
backup
filesperset 64
(archivelog all);
backup
current controlfile
tag = ctrlfile_level0backup;
release channel t1;
release channel t2;
change archivelog all crosscheck;
}
Thanks
Pete
[END]
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