Greg,

On Wed, 28 Jun 1995 13:52:12 PDT Greg Tevis said:
>We get asked this question often about whether it's better
>to use JFS files or logical volumes for the ADSM DB and log
>(and storage pool volumes).  Logical volumes have lower overhead
>so they should be more efficient, however, JFS does caching which
>helps it perform well.  Our performance group ran various tests
>on this prior to shipping the ADSM for AIX server and no
>conclusive evidence was found to support one or the other.

Can you tell us if ADSM does its own caching for database I/O?  If so,
then I would think that the JFS caching would then be superfluous overhead.
If ADSM does NOT do its own caching, then the JFS caching would be useful.

Same question for disk storage pool I/O.  Does ADSM cache in memory for
this?

Same question for log volume disk I/O.  Does ADSM cache in memory for
this?

We actually started out using raw logical volumes, and then switched
over to JFS files at the recommendation of an IBMer many months ago.
We haven't done any careful analysis of whether this helped us or not, but
the question has been bothering me a bit ever since the beginning.

We are most concerned with ADSM performance during nightly backups.
And really, we are more concerned with data throughput than with the
performance of any one system.  Do you have any recommendation for this
particular emphasis?

Thanks.
..Paul