A question for tar in the HP-UX

[Taohung]

My HP-UX v11.23, HP rx2600 server
HP DAT24 External tape driver 4/8GB DDS
The default option of DAT24 : enable rewind and compress.

When I do ..(continuously)
1) tar -cvf /dev/rmt/c2t5d0BEST /etc (enable rewind and compress)
2) tar -cvf /dev/rmt/c2t5d0NOMOD /tmp (enable rewind and disable compress)
3) tar -tvf /dev/rmt/c2t5d0BEST (Show all /etc data )
4) tar -tvf /dev/rmt/c2t5d0NOMOD (Show all /tmp data )

The data of "/etc" could not be cleared, why?

Thank you.

[Bill Hassell]

The question cannot be answered because the characteristics of the device file are unknown. The tape will be automatically rewound if the device file does not have the no-rewind feature. The only way to determine this is with the lssf command:

lssf /dev/rmt/c2t5d0BEST
lssf /dev/rmt/c2t5d0NOMOD

If you are relying on the tape position to be easily predictable, do NOT use the AT&T device files but use the Berkely files. To understand the difference, read the man page for mt.