On Mon, 15 Jun 2009, Thommy M. wrote:
In most cases compression is not desireable. It consumes CPU and
results in uneven system performance.
IIRC there was a blog about I/O performance with ZFS stating that it was
faster with compression ON as it didn't have to wait for so much data
from the disks and that the CPU was fast at unpacking data. But sure, it
uses more CPU (and probably memory).
I'll believe this when I see it. :-)
With really slow disks and a fast CPU it is possible that reading data
the first time is faster. However, Solaris is really good at caching
data so any often-accessed data is highly likely to be cached and
therefore read just one time. The main point of using compression for
the root pool would be so that the OS can fit on an abnormally small
device such as a FLASH disk. I would use it for a read-mostly device
or an archive (backup) device.
On desktop systems the influence of compression on desktop response is
quite noticeable when writing, even with very fast CPUs and multiple
cores.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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