Re: [Duplicity-talk] A couple easy questions

[Travis H.]

On Mon, Jan 01, 2007 at 08:56:16PM -0800, mike wrote:
> >If it used bzip2, you could set BZIP envar and specify -9.
> 
> it says nothing about bzip

I know, I mean, it would be nice if duplicity supported bzip2,
but it doesn't.

> it says under --no-encryption that it will
> "only output gzipped volumes" - so i assume they do gzip+gpg normally.

It turns out you can specify options in an envar with gzip, but
duplicity uses the python gzip module and not the program.
However, you're in luck:
  def gzopen(gzname, gzmode="r", compresslevel=9, fileobj=None)

So level 9 is the default, and the other part of the script
that calls this only specifies 2 arguments, so it's always 9.

> >Or just patch your
> >duplicity to use bzip2; it gives better compression anyway.
> 
> it would be nice. too bad i don't know python at all.

Well, python is easy; take a look at the tutorial on the website.  I
expect that if you have any programming experience at all it will take
about 30 minutes to learn 80-90% of the syntax, and the remaining
tasks are just looking up the documentation on the various modules.

By the way maintainers, duplicity currently uses the gzip module,
but it looks very simple to me to use bz2 instead, as it emulates
a file even more completely than gzip.

> well i assume it works like rsync -c, using a checksum, not just
> mtime/ctime/etc.

In looking through the duplicity source, it appears that when it does
use the rsync backend, no relevant options are passed to it.  Only if
it deletes does it use arguments, and those are:
"rsync --recursive --delete --exclude-from=%s %s/ %s"

> i also had a question about archive size, if there is a way to limit
> the file size, since services like S3 have a 5G single file size
> maximum, it probably wouldn't be good to make archives that large
> either. that would be an option i would love to see added.

You could create them locally then use split(1)...
-- 
``Unthinking respect for authority is the greatest enemy of truth.''
-- Albert Einstein -><- <URL:http://www.subspacefield.org/~travis/>

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