John Goerzen wrote:
> On Wed, Nov 05, 2008 at 10:40:35PM +0100, Nils Breunese (Lemonbit)
> wrote:
>> John Goerzen wrote:
>>
>>> First, the on-disk compression format makes me nervous. It
>>> appears to
>>> use the deflate algorithm, but cannot be unpacked with either gzip
>>> or
>>> unzip. It would seem that the few bytes that adding a gzip header
>>> means would be well worth it, since it would buy the ability to
>>> extract it without using specialized tools.
>>
>> You can use the BackupPC_zcat binary to decompress individual files
>> manually.
>
> Right, I'm aware of that. But that's a specialized tool. It requires
> CPAN libraries, libraries from BackupPC's perl library, etc. 20 bytes
> or so would get you something that gzip could uncompress.
Are you sure? I thought it also works on its own. Haven't tried it
though.
> There's still the question of a CRC.
I don't know about that.
>>> Secondly, I would love to be able to use bzip2 for the on-disk
>>> compression of each backup. It appears that bzip2 can be used for
>>> archives, but not the regular backups. Is this in the works
>>> anywhere?
>>
>> In my experience bzip2 is a much more resource intensive algorithm
>> than gzip. I wouldn't want to use that on my backups, they'd take
>> forever to compress.
>
> Sure, it's resource-intensive, but why not offer it? I've got a Core
> 2 Duo, and in tests using dar (similar to tar) with per-file bzip2
> compression, it performs well enough and has a space savings in the
> neighborhood of 20% over gzip on my test set.
>
> It will certainly not be right for everyone, but why not the choice?
Well, maybe because it was never implemented and you're the first
person to ask about it. :o)
Nils Breunese.
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