I’ve had a little issue trying to get more than 4GB of data onto this unit, and the usual {Google} wasn’t helping much. Checking all of the jumpers showed that hardware compression was enabled, but both tar and dump refused to go beyond 4GB of data, which was rather annoying as my root partition is only 4.5GB…

After running mt status I saw that the density was set to 19 which in the man page for mt maps to DDS, and not DDS2, so I then tried mt setdensity 36 but that failed with the rather annoying:

mt: /dev/nrst0: setdensity: Invalid argument

which is rather unhelpful, especially as I know it’s a DDS2 drive. Looking through the source code wasn’t that helpful: it just ended up as a SCSI command anyway, so I triple-checked the jumper setting (J4, D.C. Disable is OFF) and changed the Unix DIP switches from the Solaris settings (1=OFF, 2=ON, 3=OFF, 4=ON) to the Linux ones (all OFF). I’m not sure if that last stage is important as at this point I re-re-read the mt man page again and saw that density zero is listed as:

     0       Device default

So I then tried the following commands after inserting a fresh tape:

mt rewind
mt setdensity 0
mt eew 1
dump -0aet /

and 1 hour and 1 minute later I had my dump. Hurrah !