On Sep 22, 2010, at 7:17 AM, Stefan Folkerts wrote:

> De performance of a disk based storagepool will be fine at the start but will 
> degrade over time due to fragmentation, I have seen this happen on large 
> permanent use diskpools.

I think this is particularly an issue with TSM volumes implemented within file 
systems, where disk block locations are "pot luck".  (Formatting multiple disk 
pool volumes in parallel, explicitly via dsmfmt or implicitly via Define 
Volume, can cause fragmentation, as warned by the TSM Performance Tuning Guide 
and Technote 1248324.)  Implementing disk pools via raw logical volumes, where 
your platform supports that, helps avoid fragmentation issues, particularly 
where disk pool caching is turned off.

   Richard Sims    http://people.bu.edu/rbs