[GRASS-dev] GRASS raster compression & performance

Markus Neteler neteler at osgeo.org
Sun Dec 11 16:39:01 EST 2011


since my office grassdata/ becomes huge, I wonder if I should
change to zlib compression.

>From the "variables.html" page I get (btw: no mention of this in
the r.compress manual!):

    if the environment variable GRASS_INT_ZLIB exists, new compressed
rasters will be compressed using zlib instead of RLE compression. Such
rasters will have a compressed value of 2 in the cellhd file.
    Obviously, decompression is controlled by the raster's compressed
value, not the environment variable.

I wonder what the performance penalty of zlib could be. Does
anyone have experience? An advantage of stronger compression
could be that the data traffic on NFS on a cluster becomes less...

Opinions welcome,

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