>> I am currently backing  up to a tape storage pool using an ATM 155mbps ring.
>> I am not using a disk copy storage pool.  I am backing up directly to tape.
>> Currently, my average transmission rate is 2.2 MB/sec or roughly 7.6 GB per
>> hour.  IBM states that a 15 MB/sec rate is possible.  Does anyone have a
>> performance tuning tips that can help me speed up the transmission rate?
>
>Backup to disk.

Maybe, maybe not.  Over time, customers have reported that their experience
with high-performance tape drives such as the 3590 gives them better
performance when writing directly to tape.  Each site should experiment to
see what works best with their configuration (classic system tuning).

The standard advisory: ADSM is in between your client and your tape drive,
and you have to assure that it is fully tuned to maximize performance.
The server needs lots of memory, large buffer pool sizing, and fast disk
for the database.  See the Tuning Guide for all its advisories.
  Richard Sims, BU