> > Should I skip amanda's compression and use the hardware compression? > > This depends. Software compression puts more load on the machines getting > backed up, but let's you more accurately see how much data is going on > tape. Hardware compression takes load off the systems, but makes you > guess as to how much compression is going on (and thus how "big" your > tapes are).
I suggest software compression. a) Amanda keeps track of previous information about compression. After a while she gets pretty accurate in guessing how much space your file systems will use on tape. b) Hardware compression will compress all file systems. When using software compression, you get the opportunity to specify which file systems that should use _no_ compression. This is useful for file systems containing lots of already compressed files. Let's say you have an archive full of .tar.gz files or something. Hardware compression will be of no use for those files. Actually, they will probably become bigger on tape. c) You can specify if the client or the (tape) server will perform the compression, and also if it should be --fast or --best (=slow). Having said that, the load factor remains. For example, if you have many Samba file systems, the Samba server will be responsible for the compression of _all_ its file Samba systems, if 'client' is specified. The Samba server is in fact the client for those file systems. -- Ulrik Sandberg
