[mdlug] Compression and Archiving

[Jeff Hanson]

On Mon, Jan 11, 2010 at 5:11 AM, Drew <drew4096 at gmail.com> wrote:
> Squashfs seems to give me compression down to from 66% to 77% of
> original size with most of the
> files being PDFs. I had been hoping for something a bit better. Is
> there a way to specify better compression
> methods? Is there a better filesystem to use? Or would I be better
> off using something like gzip or bz2?
> I'd like to be able to mount these as loop devices.
>
> Also, can an entire DVD be a squashfs filesystem? Or does it have to
> be wrapped in an iso?

http://en.wikipedia.org/wiki/Squashfs
http://tldp.org/HOWTO/SquashFS-HOWTO/mksqoverview.html#mksqoptions

Compression options are limited to gzip or lzma.

If you use file-based approach with gzip or bz2, use a separate file
for each source file.  Tar+anything is really slow for browsing as the
entire tar has to be extracted before opening.  I prefer 7zip for
large numbers of files in a single archive as it it very fast for
opening and browsing but it doesn't handle *nix file permissions.

Also consider damage potential.  You are likely to lose more data with
a damaged DVD using a single large archive or squashfs volume than
individual files.  Individual files are much easier to recover.  A
single file or filesytem will be somewhat more space efficient due to
less overhead (a single compression header instead of one for each
archive file).

Individual files also make it easier to incrementally add to the DVD.