I am glad you asked this question as I was thinking of posting a similar question myself.
Here is our configuration:
IBM F50 4-way AIX 4.3.3 ML 11 1 GB RAM Overland Neo 4000 library with 4 Seagate LTO-1 drives, hardware compression on 2 6205 Ultra2 SCSI Interface cards (2 drives per/port with library on its own port) TSM 5.1.5.4
Before I started to play with some server side parameters (MoveBatchSize, MoveSizeThresh, BuffPoolSize), I was getting about 4-5 MB/s tape throughput on a primary pool copy operation.
After cranking up the three parameters from their defaults (MoveBatchSize (# objects) 40->1000, MoveSizeThresh (MB) 500->2048, BuffPoolSize (KB) 2048->131072) I am now getting 11-12 MB/s tape throughput on that same primary pool copy operation.
My two cents.
Marc Taylor