[rescue] Sun 20/40G 8mm tape drive (Exabyte 8900) - blocking factor / throughput ?

[vom513]

I figured this out.  I was having two issues:

- Dirty drive
- SCSI bus to bus (esp to isp) bottleneck (I’m guessing this is what it is…)

For the first one, I kept digging in this rabbit hole and threw together a PC with a SCSI card and installed FreeDOS / Debian linux dual boot.  From FreeDOS I was able to run Exabyte EXPERT software which put the drive through it’s paces and gave very detailed stats.  Before cleaning had tons of re-writes and ECC’s on reads.  After cleaning errors were close to 0 and the tests all passed.

For the second, I also tried this tape drive on the PC booted into Linux.  The SCSI card is an Adaptec 2940UW.  Throughput was textbook and what I was expecting all along.

Going back to the SS20, I tried some more tests using dd and /dev/zero / /dev/null as needed to take the esp bus HDD’s out of the equation.  When doing this, the throughput is what is expected ( >= 3 MB/s).