After fighting with our DBAs for months now about IO performance, we finally narrowed down a growing performance issue to disk fragmentation. We accidentally discovered that a copy of a database was 2x faster to backup than the original copy which lead us to the conclusion that we did actually have an issue with IO.
We ran a reallocate measure which resulted in a threshold of 3. I'm not sure exactly how this is calculated, but obviously the result is misleading. The results should have been 10 IMHO.
We ran reallocate start -f -p on the volume and it immediately reduced the backup time in half. Disk util, disk caching, latency all were significantly better after the reallocate completed.
It appears that a the Sybase full reindex basically tries to optimize by re-writing data... This process somehow causes the disk fragmentation.
I've only been able to find limited information on the reallocate command, however with this significant performance increase, there should be a whitepaper on the subject that includes the effects of reallocate on Cache, PAM, Dedup, Vmware, Databases, Exchange, etc...
Is there a TR document in the works on reallocate? If not, someone should start one.