ZfS & GEOM with many odd drive sizes

[Pawel Jakub Dawidek]

On Thu, Jul 19, 2007 at 06:19:14PM +0100, Mark Powell wrote:
> On Thu, 19 Jul 2007, Pawel Jakub Dawidek wrote:
> 
> >On Thu, Jul 19, 2007 at 11:19:08AM +0100, Mark Powell wrote:
> >>  What I want to know is, does the new volume have to be the same actual
> >>device name or can it be substituted with another?
> >>  i.e. can I remove, for example, one of the 448GB gconcats e.g. gc1 and
> >>replace that with a new 750GB drive e.g. ad6?
> >>  Eventually so that once all volumes are replaced the zpool could be, for
> >>example, 4x750GB or 2.25TB of usable storage.
> >>  Many thanks for any advice on these matters which are new to me.
> >
> >All you described above should work.
> 
> Thanks Pawel. For your response and much so for all your time spent 
> working on ZFS.
> 
> 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?

Be sure to turn off debugging, ie. remove WITNESS, INVARIANTS and
INVARIANT_SUPPORT options from your kernel configuration.
Other than that, ZFS may just be more CPU hungry...

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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