[NTLUG:Discuss] st and mt question

[Alvin Goats]

>Question.
>Then man(ual) pages for st say the 'n' prefix means non-rewinding, and 
>otherwise each device may be defined with different characteristics 
>(block size, compression, density, etc.)  What is the easiest way to 
>find out how they are defined now?

You need a tape IN the drive and let's assume you are using /dev/st0:

mt -t /dev/st0 status

will give you a current status of the drive and tape. My DDS2 drive with
DDS tape reports:

SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x13 (DDS (61000 bpi)).
Soft error count since last status=0
General status bits on (41010000):
 BOT ONLINE IM_REP_EN


mt -t /dev/st0 tell

shows where you are on the tape:

root at darkstar:/# mt  -t /dev/st0 tell  
At block 0.

mt  -t /dev/st0 densities

lists the densities that are possible for different drives:

root at darkstar:/# mt  -t /dev/st0 densities
Some SCSI tape density codes:
code   explanation                   code   explanation
0x00   default                       0x20   QIC-6GB
0x01   NRZI (800 bpi)                0x21   QIC-20GB
0x02   PE (1600 bpi)                 0x22   QIC-2GB
0x03   GCR (6250 bpi)                0x23   QIC-875
0x04   QIC-11                        0x24   DDS-2
0x05   QIC-45/60 (GCR, 8000 bpi)     0x25   DDS-3
0x06   PE (3200 bpi)                 0x26   DDS-4 or QIC-4GB
0x07   IMFM (6400 bpi)               0x27   Exabyte Mammoth
0x08   GCR (8000 bpi)                0x28   Exabyte Mammoth-2
0x09   GCR (37871 bpi)               0x29   QIC-3080MC
0x0a   MFM (6667 bpi)                0x30   AIT-1 or MLR3
0x0b   PE (1600 bpi)                 0x31   AIT-2
0x0c   GCR (12960 bpi)               0x33   SLR6
0x0d   GCR (25380 bpi)               0x34   SLR100
0x0f   QIC-120 (GCR 10000 bpi)       0x40   DLT1 40 GB, or Ultrium
0x10   QIC-150/250 (GCR 10000 bpi)   0x41   DLT 40GB
0x11   QIC-320/525 (GCR 16000 bpi)   0x45   QIC-3095-MC (TR-4)
0x12   QIC-1350 (RLL 51667 bpi)      0x47   TR-5
0x13   DDS (61000 bpi)               0x80   DLT 15GB uncomp. or Ecrix
0x14   EXB-8200 (RLL 43245 bpi)      0x81   DLT 15GB compressed
0x15   EXB-8500 or QIC-1000          0x82   DLT 20GB uncompressed
0x16   MFM 10000 bpi                 0x83   DLT 20GB compressed
0x17   MFM 42500 bpi                 0x84   DLT 35GB uncompressed
0x18   TZ86                          0x85   DLT 35GB compressed
0x19   DLT 10GB                      0x86   DLT1 40 GB uncompressed
0x1a   DLT 20GB                      0x87   DLT1 40 GB compressed
0x1b   DLT 35GB                      0x88   DLT 40GB uncompressed
0x1c   QIC-385M                      0x89   DLT 40GB compressed
0x1d   QIC-410M                      0x8c   EXB-8505 compressed
0x1e   QIC-1000C                     0x90   EXB-8205 compressed
0x1f   QIC-2100C                   

To set the default density of /dev/st0 to DDS2:

mt -t /dev/st0 setdensity 0x24


Hope this helps some!


Alvin