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1 shrik commented Permalink

Hello Peter. Because only Linear logging supports such recovery, how much of a performance impact is it, if we move away from Circular to Linear ?

2 Peter Broadhurst commented Permalink

Hi, I don't personally have any test data for the performance overhead of enabling linear logging. Deleting rather than archiving your logs (to avoid read/write contention on the FileSystem), and not using rcdmqimg if you don't need the extra reassurance of media recovery, means the overhead is limited to creating/formatting the new extents during checkpoints. The cost of this is likely to be both FileSystem specific. Maybe others in the community can comment.

3 Ugi commented Permalink

Hello Peter, <br /> This is Ugandhar from OCBC, Singapore. Can i use this tool for circular logging? Is it mandatory to stop MQ QMGR before dumping logs when we use circular logging

4 Peter Broadhurst commented Permalink

Hi Ugi, you can use the approach to a limited extent with circular logging - but you will only see what happened since the base LSN of the dmpmqlog command. <br /> That is the beginning of the recovery log file, that contains the start of the active portion of the log - e.g. when the last checkpoint happened. <br /> So even if you have a large circular log, you might only get a very small amount of history from dmpmqlog -b. <br /> You can't use dmpmqlog directly against the running qmgr, however you can use the approach in the TechNote/InfoCenter to take a 'dirty copy' of the logs and use a dummy qmgr to run dmpmqlog against that copy.