On Wed, 9 Jan 2002 at 9:44am, Kasper Edwards wrote > Im using amanda on a linux box with an old SONY-SDT5000 DDDS2 drive. > Everything works like a charm - I have actually restored some files ;) > > The question: Is it recommended to use hardware compression or should I > leave it off? When I first configured the thing a few month ago I left > compression ON, but now im not sure if it actually were a good idea.
It's completely up to you. Software compression does have a few advantages. One is that you can tell amanda the actual size of the tape rather than guessing at how much the hardware will compress stuff. A second is that, after a while, amanda will have a feel for how much each filesystem compresses and thus the estimates of how much will fit on a tape will be more accurate. Finally, gzip probably will get a higher compression ratio than hardware. *However*, hardware compression has its advantages too. If your systems don't have the cycles to spare, then hardware compression obviously takes that load off of them. Also, if your systems aren't exactly, err, state of the art, then software compression may significantly increase your backup times. Whatever you do, though, be sure not to use both. Trying to compress (in hardware) already compressed data is Bad. Your tapes will seem much, much smaller. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
