Greets everybody; One item of utility software we need for amanda is one that can change the status of the drives hw compression. As it sits now, a tape that has once been written with the HW compression turned on cannot ever have it turned back off. This may not be true of all drives, but a Seagate 4586 (dat robot) sure does it
The problem is that you can turn the dip switch off, but the drives always set it internally to whatever is on the tape IF the tape is compressed _and_ the tape is read again. So you can turn it off with mt, but the pre-read amlabel does results in its being turned back on for the renewed label write, hence a catch 22. If its on, on the tape in the drive, amlabels pre-reads will cause the drive to turn it back on and theres nothing amlabel seems capable of doing about it. This is something that we really should be able to handle with a shell script but I haven't been able to work out the ugly details. We ought to be able to do something along the lines of: mt -f /dev/whatever rewind dd if=/dev/whatever of=tempfile count=1 mt -f /dev/whatever rewind mt -f /dev/whatever datcompression off dd if=tempfile of=/dev/whatever count=1 mt -f /dev/whatever rewind dd if=/dev/whatever count=1 and have the last command spit out the tape header without the compression tally led on the drive turning itself back on. Am I on the right track or is this horse well and truely deceased? -- Cheers, Gene AMD K6-III@500mhz 320M Athlon1600XP@1400mhz 512M 98.3+% setiathome rank, not too shabby for a hillbilly
