DB2 LUW Online Reorg Strategy

We have been using online reorg extensively since DB2 UDB 8.2. Many clients that I consult with for initial performance problems or for initial migration to DB2 have no reorg strategy. In fact, many don’t know the difference between offline and online reorgs. Offline reorgs should be a thing of the past, keep that in mind although they can be used to fix space problems in the tablespace. However, most tablespace orphan space issues have been fixed in 9.7.  I have most of my clients doing online reorgs during slower periods of activity, extensively. Including index reorgs with “allow write access” specified. Some clients have been able to stay up for over a year using this strategy. So if you haven’t been using online reorgs and you are losing your down window, then online reorgs are the way to go. Size the logs appropriately before you start, doubling the size is a good starting point. Of course, experiment with starting, stopping and pausing online reorgs along with how monitoring of them before you start. Use db2pd -d <dbname> -reorgs and db2pd -d <dbname> -reorgs index to monitor status of index reorgs. So if you have been wondering if online reorgs are a good thing, in almost all cases they are. Get moving…..