Hi,
I'd like to use bzip2 with amanda for two reasons:
1. It compresses a lot better than gzip
2. More importantly -- data recovery is possible from a damaged tape.
>From bzip2's manual:
bzip2 compresses files in blocks, usually 900kbytes long. Each
block is handled independently. If a media or transmission error
causes a multi-block .bz2 file to become damaged, it may be
possible to recover data from the undamaged blocks in the file.
The compressed representation of each block is delimited by a
48-bit pattern, which makes it possible to find the block
boundaries with reasonable certainty. Each block also carries
its own 32-bit CRC, so damaged blocks can be distinguished from
undamaged ones.
With gzip and compress, in general, once a media error is encountered,
the entire remainder of the file (tar or dump in our case) is
unusable. This is why people generally shun gzip/compress for
backups, unless it's done on a per-file basis to lessen the severity
of errors. Of course, doing it on a per-file basis also lessens the
effectiveness ofcompression. The only tradeoff with bzip2 is CPU
time: it is more CPU-intensive than gzip or compress. However, when
reliability of backups is at stake, that's a tradeoff I'm quite
willing to take,
In amanda, the configuration file seems to think that the user isn't
smart enough to manually specify a compression program :-) I'd much
rather specify "gzip -9" and "gunzip" than specify "best compression"
or whatnot. Are there any plans to support this? If there were, it
would be trivial to drop in bzip2 instead of gzip with amanda.
Are there any plans to support this? I suppose I could just go into
the code with sed and s/gzip/bzip2/ but I'd prefer to do it more
elegantly if possible :-)
-- John
--
John Goerzen <[EMAIL PROTECTED]> www.complete.org
Sr. Software Developer, Progeny Linux Systems, Inc. www.progenylinux.com
#include <std_disclaimer.h> <[EMAIL PROTECTED]>
