On Jan 26, 2008, at 3:24 AM, Joachim Pihl wrote:
> So far so good, "zfs get all" reports compression to be active. Now
> for
> the problem: After adding another 300GB of uncompressed .tif
> and .bin/.cue
> (audio CD) files, compression ratio is still at 1.00, indicating
> that no
> compression has taken place.
TIFF files can how their own compression ("compressed TIFF") and many
image editors have this on by default, so you wouldn't know about it
unless you specifically looked for it. I think the TIFF spec specifies
LZW compression for this... but either way, if this is indeed the
case, zfs compression won't help with those
Now, the bin/cue file format specifies no optional compression, so
those bin files should be nothing but a raw image of 16bit PCM
audio... which you should see some (but not great) compression with.
The default lzjb compression scheme in zfs might not be terribly
effective on this type of file data being that it's optimized for
speed rather than compression efficiency. Try turning on gzip
compression in zfs instead and see if things improve.
To make that simple I'd just make a new fs (eg; pool/data/audio) and
then 'zfs set compression=gzip-4 pool/data/audio' and then mv your bin/
cue files there.
/dale
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