Tape drives

Linux supports many SCSI tape drives. Currently, we have one 8mm Exabyte drive and two 4mm DAT (one DDS3 and one DDS) drive installed on the machine astrotape, which is located in the downstairs computer room. It can be accessed through using normal UNIX tape commands (tar, mt, etc.). The Exabyte drive has a capacity of $\sim$ 8 Gby; the DAT DDS has a capacity of $\sim$ 4 Gby. The DAT DDS3 drive on astrotape has a 24 Gby capacity, and an even higher capacity DAT DDS4 drive on maritimus. Tape drive availability is summarized in the following table.

Tape drive	Host computer	Device name
Exabyte 8mm	astrotape	/dev/st? /dev/nst?
DAT 4mm (DDS)	astrotape	/dev/st? /dev/nst?
DAT 4mm (DDS3)	astrotape	/dev/st? /dev/nst?
DAT 4mm (DDS4)	maritimus	/dev/st0 /dev/nst0

The /dev/stn devices will automatically rewind after each access; the /dev/nstn will not rewind.

Occasionally, one may get I/O errors when trying to read tapes. One thing to check if this occurs is whether the block size is incorrectly set on the tape drive. In general, the tape drive block size should be set to 0, which means it should be able to adapt to whatever block size the tape was written with. You can check the tape drive setting using the command: mt -f device status, and you can change the blocksize (to 0) using: mt -f device setblk 0.