Tape drive

From UMaine Supercomputer

We have a Quantum DLT 8000 SCSI tape drive with 40GB (nominal tapes)

This is our final archival system. Typically I am writing compressed data so I turn hardware compression off. All tapes are recored using tar. Since this is a streaming tape drive performance is terrible if you use a small blocking factor (such as the default 20). Any size over 64 seems to give adequate performance, I use 256.

To turn off compression:

mt -f /dev/st0 datcompression 0

Example write command

tar -cb 256 -f /dev/st0 *

Example corresponding read command:

tar -xb 256 -f /dev/st0

NOTE that the blocking factors must match.

Another useful hint, /dev/st0 rewinds at the end of a command. Sometimes you don't want to do this, such as when you are appending to a tape. Use the device /dev/nst0 if you don't want to rewind at the end.