Compressing hippos really fast

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

Hi,


does anybody know about a compression tool which is above all capable of
compressing really fast?  The compression ratio is only a mild concern,
it's rather more important that the tool is not acting as bottleneck
when compressing files which are badly compressable.  Unfortunately
the usual compression tools are rather interested in a good compression
than in a good speed when streaming lots of data.

Here are a couple of disks which are supposed to be backed up.  Right
now this is done using a script which creats tar.gz archives of all
disks.  Some of this disks are quite big and contains many files which
are already compressed.  It turns out that gzipping these disks is *the*
bottleneck when backing up.

When not compressing, tar creates archives with 37MB/s.  When creating
tar.gz archives, the compression takes so much time that the speed goes
down to 6MB/s.  Using gzip --fast doesn't help much.  bzip is a lot
slower than gzip.

So the question is, does anybody know a compression tool which can be
used with tar, which doesn't slow down the backup by a factor of 6?  It
would be cool to have a tool which is as quick as the hardware
compression used in modern tape drives, but that's just dreaming...


May the hippos be with you,
Corinna