That is something I am curious about, not being an AIX expert:

What is being logged to the JFS log that creates overhead in the TSM case?
I thought the JFS log was necessary because of changing files in the JFS
filesystem.
But TSM DB, LOG, and STGPOOL volumes (really files) are pre-formatted; their
size does not change.
So what is the JFS overhead when TSM is writing into those files?

Thanks!