On Wed, 21 Oct 2009, Marc Bevand wrote:
Bob Friesenhahn <bfriesen <at> simple.dallas.tx.us> writes:
[...]
X25-E's write cache is volatile), the X25-E has been found to offer a
bit more than 1000 write IOPS.
I think this is incorrect. On the paper the X25-E offers 3300 random write
4kB IOPS (and Intel is known to be very conservative about the IOPS perf
numbers they publish). "Dumb" storage IOPS benchmark tools that don't issue
parallel I/O ops to the drive tend to report numbers less than half the
theoretical IOPS. This would explain why you see only 1000 IOPS.
The Intel specified random write IOPS are with the cache enabled and
without cache flushing. They also carefully only use a limited span
of the device, which fits most perfectly with how the device is built.
There is no mention of burning in the device for a few days to make
sure that it is in a useful state. In order for the test to be
meaningful, the device needs to be loaded up for a while before taking
any measurements.
Device performance should be specified as a minimum assured level of
performance and not as meaningless "peak" ("up to") values. I repeat:
peak values are meaningless.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
