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Re: tape drive will not seek, and is always at block 0


You seem to be using the device /dev/st0 which is a SCSI tape device. There is no problem with using that device, but it will always do a rewind after every completed access to that device. So after you have written a tar file to the device, it will do a rewind afterwards.

You wil need the device /dev/nst0. The "n" stands for no-rewind. After writing to that device, the tape position stays at the end of the tape. Try using the following commands:

mt -f /dev/nst0 rewind
tar cvf /dev/nst0 $HOME
mt -f /dev/nst0 status


Dave Harrison wrote:
Hello all,

I'm having problems with my tape drive.  I am able to write to it
with tar, and I can read back from it the same way.  However I can't
'mt seek' or 'mt fsf' to be able to write a second chunk onto the tape
after the first.

There don't appear to be any problems with the drive as this dmesg
extract shows :

scsi2 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36
        <Adaptec 29160N Ultra160 SCSI adapter>
        aic7892: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs

(scsi2:A:6): 80.000MB/s transfers (40.000MHz, offset 32, 16bit)
  Vendor: ARCHIVE   Model: Python 06408-XXX  Rev: 9050
  Type:   Sequential-Access                  ANSI SCSI revision: 03
PCI: Enabling device 0000:03:07.0 (0016 -> 0017)
PCI: Found IRQ 11 for device 0000:03:07.0
PCI: Unable to reserve mem region #2:1000@dfefe000 for device 0000:03:07.0
aic7xxx: <Adaptec AIC-7892 Ultra 160/m SCSI host adapter> at PCI 3/7/0
aic7xxx: I/O ports already in use, ignoring.
st: Version 20041025, fixed bufsize 32768, s/g segs 256
Attached scsi tape st0 at scsi2, channel 0, id 6, lun 0
st0: try direct i/o: yes (alignment 512 B), max page reachable by HBA 1048575

and an 'mt status' seems to be successful as well :

SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 512 bytes. Density code 0x26 (DDS-4 or QIC-4GB).
Soft error count since last status=0
General status bits on (41010000):

But no matter what I do, the drive always seems to be at block zero.  I
try writing a file to tape with tar, which should leave the tape at the
end of that chunk of data ready for the next write, but when I do an 'mt
tell' I get Block 0.

I've tried using a range of kernels, including 2.4.27, 2.6-686-2, and a
custom 2.6.9 and a custom 2.6.10.

The system itself is up-to-date against the sarge tree, and mt-st is up
to date as well.

Any help or suggestions would be greatly appreciated.


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