ZfS & GEOM with many odd drive sizes
M.S.Powell at salford.ac.uk
Thu Jul 19 19:34:04 UTC 2007
On Thu, 19 Jul 2007, Doug Rabson wrote:
> On Thursday 19 July 2007, Mark Powell wrote:
>> Should I expect much greater CPU usage with ZFS?
>> I previously had a geom raid5 array which barely broke a sweat on
>> benchmarks i.e simple large dd read and writes. With ZFS on the same
>> hardware I notice 50-60% system CPU usage is usual during such tests.
>> Before the network was a bottleneck, but now it's the zfs array. I
>> expected it would have to do a bit more 'thinking', but is such a
>> dramatic increase normal?
>> Many thanks again.
> ZFS does a checksum on every block it reads from the disk which may be
> your problem. In normal usage, this isn't a big deal due because many
> reads get data from the cache.
I've turned off checksums, but still my machine is struggling. I think my
Athlon XP is a little old for all this work :( Any other tips for speeding
Mark Powell - UNIX System Administrator - The University of Salford
Information Services Division, Clifford Whitworth Building,
Salford University, Manchester, M5 4WT, UK.
Tel: +44 161 295 4837 Fax: +44 161 295 5888 www.pgp.com for PGP key
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