ZfS & GEOM with many odd drive sizes

[Mark Powell]

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 
zfs up?
   Cheers.

-- 
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