>Has anyone tried raw vs. AIX jfs for TSM DB performance?
Joseph - This has historically been discussed on the List. The Tivoli
manuals advise against the use of raw logical volumes, but you
can certainly do so if you want. Overall, performance is pretty much a
"wash".
>The other question I posed to IBM TSM Support was how to configure the 3 -18GB
>SSA disks: Three separate filesystems, each with a DB volume file, or one
>filesystem striped across all three disks, providing TSM one DB volume. They
>were unable to tell me whether TSM would manage the three DB vols in parallel or
>serial, but felt that the three vs. one striped was the way to go. Now that I
>am done, I see, using iostat, that during a DB backup it is only accessing one
>drive of the three at a time, showing me that TSM uses these volumes
>sequentially, not in parallel. Would I not get better TSM DB performance with
>one logical volume/filesystem striped across all three drives? If not, why? If
>so, large or small stripe size?
Tivoli management should do something about TSM Support people who don't know
squat about TSM. It's well known that TSM performance benefits from more
volumes in devoting a thread to each volume, and that threads are parallel.
This will result in better performance when there are multiple client sessions
occurring. But ADSM/TSM utility functions have historically been
single-threaded operations. That will hopefully improve over time.
But, generally, you want more volumes, not fewer.
Richard Sims, BU
