On Fri, Sep 24, 1999 at 10:36:38AM +0200, Christian Brandt wrote:
> Charlie & wrote:
>
> > It also gives very good compression (much better than gzip), but uses a lot
> > of CPU so this is not useful for running a fast tape at full speed.
> > (I get 66% of a P2-450 used writing to a QIC-250 that does 80K/s.)
>
> Well, only part ontopic, but if it is about effiziency, try szip
> (slower than bzip2) and ppmz (incredible slow and efficient) - visit
> http://act.by.net/ and be stunned by ppmz reducing the same source.tar
> to a third in comparision with gzip.
>
I've found szip to be faster than bzip2 normally, but I wouldn't recommend
it for backups as there is no protection from errors. (you could szip
files individually, but this would give worse efficiency than bzip2.)
The copy of ppmz I got used about 100KB of memory per 1KB of file size, with
no working way of limiting memory use. So unless there is a non-leaking
version somewhere this isn't very useful.
In either case, I guess a blocking filter script could be used (split,
CRC, add blocks with CRCs to a second tar). This could be reasonably
robust but not very efficient - I'll stay with bzip2 for now.
--
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