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rman maxsetsize

From: <Stephen.Lee_at_DTAG.Com>
Date: Fri, 18 Jun 2004 09:33:14 -0500
Message-ID: <>

I'm still experimenting with backing up to disk then copying to tape. Since we don't have control of Networker settings like total parallelism and target parallelism per tape drive, and sometimes enterprising SA's experiment with these, a problem can happen (read on).

My script starts up a number of save commands equal to the total parallelism as determined by
/usr/opt/networker/bin/nsradmin -s $NSR_SERVER <<-XXX

   show parallelism
   print type:nsr
} | /usr/bin/sed -n '/parallelism/s/\(.*\)\(parallelism: *\)\([0-9][0-9]*\)\(.*\)/\3/p'`

The commands are started in the background:
/usr/opt/networker/bin/save -i -c "$NSR_CLIENT" -s "$NSR_SERVER" -e
"$EXPIRE" -b oracle "${DIR}/${i}" >> "$LOGFILE" 2>&1 &

Then the following controls the number of save commands running at any one time:
while [ `jobs | /usr/bin/wc -l` -ge $MAX_JOBS ]; do

   sleep 59
   jobs > /dev/null 2>&1
   sleep 1
Then loop back around to start another save command.

Now suppose we have 4 tape drives and "somebody" has set total parallelism to 20 and target sessions per drive to 1 (why would I use these figures for an example?). What can happen is that Networker will grab the first tape drive that is ready to write (i.e. that drive doesn't need to swap tapes, or relabel a tape, etc.) and pile all or most of the sessions onto that drive. If rman's save sets are somewhere around 30 Gb, this results in a bunch of stuff getting assigned to one drive. As that drive fills up and must do a tape swap, the sessions have become best buds and will faithfully stick together even though they must move to one of the other drives.

To limit the number of bytes that can get stacked up on one drive, I had what I thought was a grand idea to use the maxsetsize parameter to limit the rman save sets to 4GB. Well, rman decided it didn't like that:

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup command at 06/17/2004 17:15:43 RMAN-06183: datafile or datafilecopy larger than SETSIZE: file# 10

Would there, perchance, be any among the rman cognoscenti, who could shine a light on the finer points of the maxsetsize parameter? (or provide a good URL to said light.) The size of the data file listed above is 32000M or 34168840192.

The version here

By the way: I think there was no 9.1 because of the agreement that Oracle does the even numbered version, and Microsoft does the odd numbered versions. (ms/pc-dos)

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Received on Fri Jun 18 2004 - 09:30:33 CDT

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