Hi Richard,
We backup our Oracle database via two channels so the data is split onto
two different tapes. Therefore we can use two channel restores.
Four channel restore doesn't make any sense as the other two extra
channels can't mount the tapes which are already in use by the first two
restore sessions.
Hope this helps
Best Regards,
Oscar
UNIX/TSM/SAN Administrator | ING Direct
410 Thames Valley Park Drive, Reading, Berkshire, RG6 1RH
Tel: 0118 938 1990 l Email: Oscar.kolsteren AT ingdirect.co DOT uk
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Richard Rhodes
Sent: 07 January 2009 14:16
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] TDP for Oracle - multi channel restore
Hello,
We are still fairly new to RMAN/TDPO backups, and trying to understand
behavior.
We have one 10tb database that performs RMAN backups to TSM using one
tape drive (one channel). Oracle datafiles are interleaved (not sure of
the level).
We are now performing a full restore on this database. The dba
allocated
4 channels for the restore (4 tape drives). We started getting session
timeouts. It looks like Oracle was asking for aggregate files on
different
channels that in TSM are on the same tape. This caused tape contention
and session timeouts. The restore was stopped and changed to a
single channel.
I've been trying to find info on issues/limitations around RMAN/TDPO
restores
with multiple channels, but not finding much info.
Questions:
1) Does the number of channels on a restore have to be the same or less
than the number used for the backup?
2) Is it even possible to do multi channel restores? In other words,
does
RMAN have knowledge of the tape volumes so as to not cause
tape contention across channels?
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