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From: Christer Solskogen <christer.solskogen@gmail.com>
Date: Wed, 26 Jan 2011 21:47:15 +0100
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To: Dan Nelson <dnelson@allantgroup.com>
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Cc: "O. Hartmann" <ohartman@mail.zedat.fu-berlin.de>,
	freebsd-questions@freebsd.org
Subject: Re: FreeBSD 9/ZFS: Striped Pool (2 disks) migrating to mirror (onto
 additional disk)
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On Wed, Jan 26, 2011 at 9:42 PM, Dan Nelson <dnelson@allantgroup.com> wrote=
:

> ZFS lets you add and detach mirrors on the fly, since you're not changing
> the capacity of the pool itself. =A0Sure, you're going to lose the conten=
ts of
> the large 2TB drive, but that's sort of assumed. =A0You can't convert 4TB=
 of
> non-mirrored disks into 2TB of mirrored disks without losing 2TB of space=
.
> Just make sure you have less than 2TB total used data on all volumes, and
> copy the data off the 2TB filessytem onto the striped 1+1TB one before
> repartitioning and adding the mirrors.
>
> =A0zpool attach [-f] pool device new_device
>

The problem is that you cant attach a drive to a vdev that consists of
two striped disks.

--=20
chs,