Hi Sean -
We have various RMAN clients using anywhere from 1 to 4 channels - we do not
have collocation turned on, because of problems such as you mentioned. To
increase our times, we turned off collocation <we have a separate tape pool
for our RMAN clients> and increased channels where necessary. I am not sure
how much your clients back up - but ours back up anywhere from 100gig to 250
gig at night and do archives <which are only about 1 gig> during the day.
In either case, if you do opt to keep collocation turned on, the answer to
your question is yes, it will wait for the media and then start writing the
data as it would if it was not waiting. We have had this situation one time
when we did not realize that the tape pool got low. However, we have found
that RMAN work more efficiently when collocation is turned off and multiple
channels are ran and restore speed was not effected.
Terry
-----Original Message-----
From: Sean M English/Charlotte/IBM [mailto:[EMAIL PROTECTED]]
Sent: Thursday, October 19, 2000 12:03 PM
To: [EMAIL PROTECTED]
Subject: RMAN question??
I have a question about a client that is using RMAN to backup there Oracle
databse to TSM.
TSM Server:
3.7.3.6 on AIX 4.3.2
We recently changed the backup method for the Oracle databases from going
to disk to going directly to tape. We created a unique nodename for each of
the Oracle DB servers. These servers are in there own domain. When we first
tested this, we saw great results (in terms of speed) to backup the Oracle
DB. However, now when the servers run their backups each night, they are in
a constant Receive Wait and the time to back them up as actually increased.
Currently they are allocating one channel for each backup. The reasoning
behind one channel was that anything other than 1 channel (i.e. 2 channels)
the other one would be in a media wait because of colocation. My question
is, has anyone else seen where a backup like this was in a constant receive
wait when using only on channel? I have a thought, but I am not 100% sure
if it would solve my problem because I am not 100% sure on how RMAN groups
its data. My thought is if you run 2 channels, one will be running and the
other waiting. However, will that second channel already have the data
grouped together and ready to transfer when the other one gets finished?
Let me know if anyone else has seen this. If I need to provide more
infomation, let me know. Thanks for the help.
Regards,
Sean M. English
Distributed Storage Management/TSM
IBM Global Services South, Charlotte, NC
External: (704)594-2232 T/L: 8-794-2232
Pager: (800)946--4646 PIN: 1428698
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