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

[Dave McGuire]

On December 24, 2023 5:22:51 PM vom513 via rescue <rescue at sunhelp.org> wrote:
> 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).

  Excellent.

  I looked for EXPERT a year or so ago and wasn't able to find it. Would you mind sending me a pointer?  Thanks!

                -Dave

--
Dave McGuire, AK4HZ
New Kensington, PA