SCSI tape [more info]

[T. Horsnell]

>>T. Horsnell wrote:
>>...
>>> 
>>> When I put the lib back onto the Alpha, two test files (tapetest500K
>>> and tapetest50M) written on the Opteron and read back on the Alpha,
>>> matched the files as read back on the Opteron. This convinces me
>>> that its (at least) a 'write' problem.
>>> 
>>
>>Is it just the library you move, or can you also try
>>to move the SCSI controller and cables?
>
>I just move the library, but I've swapped cables as well.
>I also contacted the author of the st driver and he reckons
>I should try a different sort of SCSI adapter. I'm
>coming to the same conclusion, but perhaps I'll try the
>author of the aic79xx driver first, since I'll have to
>buy an adapter in order to try things.
>

I found A PC running FC3 (kernel 2.6.10-1.741_FC3) which had
an Adaptec 29160 SCSI adapter in a 32-bit PCI slot.
I connected my SDLT2 library to it and repeated my tests.
Everything worked!.

Adaptec 39320 uses aic79xx driver
Adaptec 29160 uses aic7xxx driver

I took the 29160 out of the PC, intalled it in the Opteron
box (into a 64-bit PCI-X slot) and repeated the tests. Failure.
The Opteron has 4 kernels available:
 2.6.10-1.770_FC3smp
 2.6.10-1.770_FC3smp
 2.6.10-1.770_FC3 
 2.6.10-1.770_FC3 
I tried them all. Failure.
I even booted from a Knoppix CD with 2.4.27.
(This presumably means I'm running a 32-bit kernel on a 64-bit box). Failure.

I remembered I had a desktop Compaq SDLT1 tapedrive on one of my systems.
I tried that on the 29160 adapter. Success.
I tried it on the 39320 adapter. Success. 
Is it some sort of datarate problem I ask myself (the
SDLT1 is about half the speed of the SDL2) and the SDLT2
worked on the PC.
I moved the 2960 out of the PCI-X slot into a PCI slot
and tried again with the 5 Kernels listed above. Failure.

I'm now running out of ideas/energy/hardware.
With my original configuration, (Opteron, 2.6.10-1.770_FC3smp,
Adaptec 39320, dual SDLT2) I can get verified tar dumps
of at least 4GB (I havent tried anything bigger) provided I
use a record size > 32768 (64*512). 65536 (256*512) works fine,
as does 131072 (256*512). 32768 fails.

Is it time to file a bug report? Who with?

Thanks for any and all suggestions,

Terry.