Joshua Baker-LePain wrote:

On Thu, 19 Jun 2003 at 4:57pm, Tom Brown wrote

ISTR you saying this is Linux?  If so, then 'mt compression 0' should do
it.  You can check the status by pointing 'tapeinfo' (from the mtx
distribution) at the generic device associated with your tape drive.

It is linux yes - will amanda use this command before writing to this device
when amanda runs normally? How can one be sure that the hardware compression
is permanently off?

I just put that command in the script that runs amdump each night. You can also play with stinit, but I've never bothered.

On Linux this does not help.  Because despite the setting of the "mt"
command,  the system adapts itself to the setting of the current
tape if you read from it.  Before writing the new label amanda reads
the label, thereby reverting to the setting that was used when the tape
was labeled.
Even amlabel first reads the tape to check, thereby falling into
the same trap.
The only way to switch a tape is: first set the mode "mt ...", and write
some data on it, *without* any intervening reads.  (Try "mt status"
afterwards to verify the status of the drive.)

To configure a drive during boot or on module load),
configure a file /etc/stinit.def  (see cryptic manpage for "stinit",
and read README.st in the kernel sources). E.g. for
a DDS-2 drive (the manufacture and model must be
exactly as reported by the scsi probes):

$ cat /etc/stinit.def
# DDS-2 drive
manufacturer=ARCHIVE  model = "Python 02635-XXX" {
 can-bsr can-partitions auto-lock
 mode1 blocksize = 0 compression = 0
 #mode2 blocksize = 512 compression = 0
 #mode3 blocksize = 0 compression = 1
 #mode4 blocksize = 512 compression = 1
}