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Message Posted: Tue, 19 Nov 2002 @ 21:48:59 GMT
We use permanent journals in our production OLTP environment. We dump the journals to disk every hour and delete the saved journal. At the end of the day we copy all the hourly dumps onto one tape. We also dump the tables twice a week. We use a MVS scheduling system for this.
We only allocate 2 GB for the journal table, but it rarely goes about 50MB.
In the rare event that we do an MLOAD on one of the tables, we will dump the table, turn journaling off, perform the MLOAD, and then turn the journaling back on. If you do not turn the journaling off or increase the journal size, the journal may run out of space while the MLOAD is running (I know from experience).
We have not found any performance impact because of journaling.
We journal in the event that one of our interfacing applications would have a failure and we would need to try to sync our data up. Thanks goodness, we have never had to recover and rollforward our tables.
We also do a pretty nifty thing. We copy our tables onto another machine that is read only, and use the journal copies to updates those tables and keep them in sync with out production OLTP tables. [Do not try this on V2R4.1.3 unless you are at patch level 30 because it will cause a restart.]
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