zfs drive configurations?

Dan Nelson dnelson at allantgroup.com
Sat Jun 9 03:04:21 UTC 2007

In the last episode (Jun 09), Josef Karthauser said:
> On Fri, Jun 08, 2007 at 06:17:24PM -0700, Bakul Shah wrote:
> > > What if I have 5 200gb drives configured as a raidz pool, and
> > > then I replace one of the 200gb drives with a 400gb one. 
> > > Operationally what would I do?
> > 
> > I believe you can do something like
> > 
> >     zpool replace <pool> <device>
> > 
> > The new device will get "resilvered" -- get all the missing data
> > put on it and then brought up for operation.  This can take a
> > while.
> > 
> > Note that you will not be able to use the extra disk until *all*
> > the disks in a group (mirror or raid) have been replaced with
> > bigger disks.
> Does it make sense to partition my disks into some nominal smaller
> chunks: D1a-g, D2a-g, ... D5a-g and run a number of raidz across the
> drives in parallel, D1a D2a .. D5a, etc?

Won't help.  When you replace a new disk, you'll need to either
manually create larger a-g partitions and have to wait for all the
drives to be replaced with high-capacity ones (so zfs can use the extra
space in each partition), or add some more partitions h-m and wait for
all the drives to be replaced with high-capacity ones (so you can
create another raidz in the new partitions).  It's also much easier to
just give zfs the entire disk, as you don't have to parttion anything,
and when you do swap in the last high-capacity disk, you will
automatically see the new space.

	Dan Nelson
	dnelson at allantgroup.com

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