[arch-general] Unable to use tape drive

[Michal Soltys]

On 11-08-24 08:49, Vitor Garcia wrote:
> Good morning.
>
> I have been trying to my Dell LTO-120 SCSI Tape Drive on Arch without
> success.
>
> I have tried to run $ modprobe st, but still, I have no /dev/st0 and
> neither /dev/nst0. dmesg | grep -i tape shows nothing too.
>
> Is there anything I'm missing here? Dell's user manual says that the
> drive should work out of the box on linux.
>
>
> Best regards,
> Vitor
>

Though I'm past arch user, two common things that comes to mind:

1) is your scsi (sas) controller recognized at all ? (I assume you don't 
actually try to connect that to a sata port) Maybe you forgot about 
proper driver in your kernel ?

2) have you rescanned scsi bus after powering on the drive ? (shouldn't 
be necessary with modern sas controller and pretty new lto drive, but 
still ... won't hurt)

ad.1

You should have some entry in /proc/scsi

For dmesg entries, check your boot time dmesg (if I remember correctly, 
arch used to save that to /var/log/dmesg.log). Any boot time info might 
be long gone when just checked by dmesg.

ad.2

echo "- - -" >/sys/class/scsi_host/hostNNN/scan

Where NNN is the number of controller where your tape drive is attached.

For example, in my case (I have lto2 driver and old u160 controller):

ls -al /proc/scsi/sym53c8xx/
-rw-r--r-- 1 root root 0 2011-08-24 20:20 6
-rw-r--r-- 1 root root 0 2011-08-24 20:20 7

then echo "- - -" >/sys/class/scsi_host/host6/scan
then echo "- - -" >/sys/class/scsi_host/host7/scan

Then you should have devices in /dev after that. In dmesg you should 
have something like (after rescan):

scsi 6:0:6:0: Sequential-Access HP       Ultrium 2-SCSI   F63D PQ: 0 ANSI: 3
scsi target6:0:6: Beginning Domain Validation
scsi target6:0:6: FAST-80 WIDE SCSI 160.0 MB/s DT (12.5 ns, offset 62)
scsi target6:0:6: Domain Validation skipping write tests
scsi target6:0:6: Ending Domain Validation
scsi 6:0:6:0: Attached scsi generic sg2 type 1
st: Version 20100829, fixed bufsize 262144, s/g segs 256
st 6:0:6:0: Attached scsi tape st0
st 6:0:6:0: st0: try direct i/o: yes (alignment 4 B)