Monitoring tape drive usage on SLES 9 server

On an AMD64 SLES 9 SP3, I have 6 Ultrium LTO3 tape drives.
I've been searching for hours how to monitor the transfer rate to these
drives. I couldn't find any kernel counter that would indicate the
bytes transfered through the character devices corresponding to each
drive.

I'm coming from Solaris, on which you can monitor tape activity with
iostat (and probably many other tools and kstat).

The iostat project for linux can monitor block devices (basically
disks) but they never speak of char devices like tapes.

Maybe I have a bad approach of the question.

I also heard about a tool provided by HP but the papers are not clear
about what it does and if it is HP hardware related.

Any ideas ?

Thanks.

Houarn