Erik Trimble said the following, on 06/02/2010 07:16 PM:
Roman Naumenko wrote:
Recently I talked to a co-worker who manages NetApp storages. We
discussed size changes for pools in zfs and aggregates in NetApp.
And some time before I had suggested to a my buddy zfs for his new
home storage server, but he turned it down since there is no
expansion available for a pool.
And he really wants to be able to add a drive or couple to an
existing pool. Yes, there are ways to expand storage to some extent
without rebuilding it. Like replacing disk with larger ones. Not
enough for a typical home user I would say.
And this is might be an important for corporate too. Frankly speaking
I doubt there are many administrators use it in DC environment.
Nevertheless, NetApp appears to have such feature as I learned from
my co-worker. It works with some restrictions (you have to zero disks
before adding, and rebalance the aggregate after and still without
perfect distribution) - but Ontap is able to do aggregates expansion
nevertheless.
So, my question is: what does prevent to introduce the same for zfs
at present time? Is this because of the design of zfs, or there is
simply no demand for it in community?
My understanding is that at present time there are no plans to
introduce it.
--Regards,
Roman Naumenko
ro...@naumenko.com
Expanding a RAIDZ (which, really, is the only thing that can't do
right now, w/r/t adding disks) requires the Block Pointer (BP) Rewrite
functionality before it can get implemented.
We've been promised BP rewrite for awhile, but I have no visibility as
to where development on it is in the schedule.
I though it's about hard defined udev configuration when a raidz is created.
But anyway, it's just not there...
--Roman
ro...@naumenko.ca
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