On Tue, Apr 08, 2003 at 02:55:04PM +0200, Toralf Lund wrote:
> A question a bit on the side:
> 
> I've been looking for a new drive or autoloader, and I notice that some 
> vendors now assume a hardware compression ratio of 2.6:1 in their 
> advertising material. Which leads me to the question in the subject; has 
> anyone ever compressed real data that much? Or even achieved a ratio of 
> 2:1, which is also frequently assumed? (In conjunction with backups, that 
> is.) The best I've done with Amanda is about 1.8:1, but that's for 
> software compression, of course.

If you are using gzip you can check your own.
It is in curinfo/DLE/info.

Here are some figures I just pulled from some of my info files.

        /w/jg1              0.200323
        /w/tape8            0.352335
        /                   0.393134
        /opt                0.398975
        /usr                0.426910
        /w/dutch            0.454703
        /export             0.466952
        /var                0.484221
        /net/winnie/C       0.525476
        /win/c              0.551328
        /w                  0.563358
        /net/winnie/E       0.644513
        /net/winnie/D       0.738696
        /images             0.747967
        /u2                 0.754721
        /w/Packages         0.977246
        /w/InstalledPkg     0.977883

Note the first DLE gets an almost 5:1 compression (to 20%)
while the last couple, mostly *.gz files, compress nada.

I deleted two empty file systems that show a 1:3.2 expansion.
Gotta file at least 1 32K block on tape :)


-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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