Hardware compression
There are multiple methods to set (turn off) hardware compression.
- Using stinit command: stinit(8) command initializes the SCSI tape drives at the system startup by sending driver ioctl commands. Use "comp" field in /etc/stinit.def configuration file to configure hardware compression for each type of tape.
- Use mt(1) command to turn off hardware compression at boot time. For example:
# mt -f /dev/st0 compression 0
Please note that compression information is not stored on the tapes ident header block until the tape has been written to.
Procedure for turning off compression and labelling tapes
- Label the tape
- Rewind the tape
- Read the label to a file using dd command
- Turn off tape compression using mt(1) command. See above.
- Re-write the label block and write more /dev/zero blocks to flush its buffers.