On September 7, 2006 12:25:47 PM -0700 "Anton B. Rang" <[EMAIL PROTECTED]>
wrote:
The bigger problem with system utilization for software RAID is the
cache, not the CPU cycles proper. Simply preparing to write 1 MB of data
will flush half of a 2 MB L2 cache. This hurts overall system performance
far more than the few microseconds that XORing the data takes.
Interesting. So does this in any way invalidate benchmarks recently posted
here which showed raidz on jbod to outperform a zfs stripe on HW raid5?
(That's my recollection, perhaps it's a mischaracterization or just plain
wrong.) I mean, even if raid-z on jbod in a filesystem benchmark is a
winner, when you have an actual application with a working set that is
more than filesystem data, the benchmark results would be misleading.
Ultimately, you do want to use your actual application as the benchmark,
but certainly generic benchmarks should at least be helpful.
-frank
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