Have y’all ever failed back to a previous version of DB2 after few weeks. Try it…its a nightmare ! Failing back during a migration window is pretty easy if you are doing a side by side migration. I had recently migrated to from DB2 V8.2 to DB2 V9.5 , after a few weeks, the application software vendor tells us, they were wrong in their documentation that stated they support DB2 V9.5, but they do support DB2 V9.1 . Even though we have been running the application on DB2 V9.5 for couple of months in our test system without any issues.
When I checked the DB2 manuals and site, I didn’t see any way of falling back after few weeks of usage. Luckily I hadn’t migrated my production system…thank god ! I need to fall back on my QA system, which is used pretty heavily and data is changed very often. The manual says to restore the pre migrate offline back, but this means I will lose all the data since then.
The only method I figured how I can do it is :
Create a new instance under V8.2
Create database and schema on v8.2 instance using db2look from V9.5 database
Unload data from V9.5 database and load it to V8.2 database
Shutdown the V9.5 instance
Change the port number / SVCENAME of V8.2 instance with the one in V9.5 instance
Drop the V9.5 database and instance once validation is complete.
I wish there is an unload feature in LUW as there is in Z/os. Instead of bringing down row at a time, wish it could bring a page at a time.