Torrey McMahon writes:
> Nicolas Dorfsman wrote:
> >> The hard part is getting a set of simple
> >> requirements. As you go into
> >> more complex data center environments you get hit
> >> with older Solaris
> >> revs, other OSs, SOX compliance issues, etc. etc.
> >> etc. The world where
> >> most of us seem to be playing with ZFS is on the
> >> lower end of the
> >> complexity scale. Sure, throw your desktop some fast
> >> SATA drives. No
> >> problem. Oh wait, you've got ten Oracle DBs on three
> >> E25Ks that need to
> >> be backed up every other blue moon ...
> >>
> >
> > Another fact is CPU use.
> >
> > Does anybody really know what will be effects of intensive CPU workload
> > on ZFS perfs, and effects of ZFS RAID CPU compute on intensive CPU
> > workload ?
> >
> > I heard a story about a customer complaining about his higend server
> > performances; when a guy came on site...and discover beautiful SVM RAID-5
> > volumes, the solution was almost found.
> >
>
> Raid calculations take CPU time but I haven't seen numbers on ZFS usage.
> SVM is known for using a fair bit of CPU when performing R5 calculations
> and I'm sure other OS have the same issue. EMC used to go around saying
> that offloading raid calculations to their storage arrays would increase
> application performance because you would free up CPU time to do other
> stuff. The "EMC effect" is how they used to market it.
>
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I just measured quickly that a 1.2Ghz sparc can do [400-500]MB/sec
of encoding (time spent in misnamed function
vdev_raidz_reconstruct) for a 3 disk raid-z group. Bigger
groups, should cost more but I'd also expect the cost to
decrease with increase CPU frequency.
Note that, the raidz cost is impacted by this:
6460622 zio_nowait() doesn't live up to its name
-r
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