[OmniOS-discuss] Zpool export while resilvering?

[Richard Elling]

> On Jun 9, 2015, at 12:00 PM, Narayan Desai <narayan.desai at gmail.com> wrote:
> 
> You might also crank up the priority on your resilver, particularly if it is getting tripped all of the time:
> http://broken.net/uncategorized/zfs-performance-tuning-for-scrubs-and-resilvers/ <http://broken.net/uncategorized/zfs-performance-tuning-for-scrubs-and-resilvers/>
>  -nld

In general, yes this is a very good post. However, for more recent ZFS and certainly
the lastest OmniOS something-14 release, the write throttle has been completely
rewritten, positively impacting resilvers. And, with that rewrite, there is a few more
tunables at your disposal, while the old ones fade to the bucket of bad memories :-)

In most cases, resilver is capped by the time to write to the resilvering device.
You can see this in iostat "-x" as the device that is 100% busy with write workload.
That said, for this specific case, the drives are not actually failed, just taken offline,
so you could have a short resilver session, once they are brought back online.
 -- richard

> 
> On Tue, Jun 9, 2015 at 1:31 PM, Dave Pooser <dave-oo at pooserville.com <mailto:dave-oo at pooserville.com>> wrote:
> >This is probably a silly question, but I¹ve honestly never tried this and
> >don¹t have a test machine handy at the moment ­ can a pool be safely
> >exported and re-imported later if it is currently resilvering?
> >
> >In the way of a bit of background, I have a pool made up with thirty or
> >so 4TB Seagate disks with a firmware issue that results in their max temp
> >being set at 40C as opposed to 60C. This particular pool is
> > in an office building in Texas, in an air-conditioned server room. The
> >condenser for this unit is in the building¹s plenum and when the building
> >a/c goes off over weekends in the summer my server room a/c struggles and
> >temps run up to about 85F or so. This
> > is causing my pool to drop random disks lately (fmadm reports high temp
> >and they get marked as removed from the pool), and I¹ve only just
> >narrowed it down to this firmware issue. Seagate firmware update utility
> >is apparently Windows only, so the disks must
> > come out for the firmware update, but the pool is resilvering several
> >disks with days remaining, hence my original query.
> 
> Not an answer to your question, but the approach I'd take is renting a
> portable 110V or 220V A/C unit from somebody like spot-coolers.com <http://spot-coolers.com/> to get
> you through the resilver, then apply the firmware update. (And then I'd
> start trying to convince management that it's worth adding a unit
> permanently -- our Office Pro 24 24000BTU/hr cost us under $4k back in
> 2011.)
> --
> Dave Pooser
> Cat-Herder-in-Chief, Pooserville.com
> 
> 
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