FreeBSD 9/ZFS: Striped Pool (2 disks) migrating to mirror (onto additional disk)

O. Hartmann ohartman at
Wed Jan 26 21:57:27 UTC 2011

On 01/26/11 21:47, Christer Solskogen wrote:
> On Wed, Jan 26, 2011 at 9:42 PM, Dan Nelson<dnelson at>  wrote:
>> ZFS lets you add and detach mirrors on the fly, since you're not changing
>> the capacity of the pool itself.  Sure, you're going to lose the contents of
>> the large 2TB drive, but that's sort of assumed.  You 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.
>>   zpool attach [-f] pool device new_device
> The problem is that you cant attach a drive to a vdev that consists of
> two striped disks.
All right, I see there is no way without any kind of trade-off.

My thinking was simple, I thought since the two physical 1TB disks build 
one joint pool of 2TB overall capacity, I could simply 'mirror' this 
pool to another disk of the same capacity.
Is there a way to 'send' via ZFS the data of the pool to the backup 
disk, like a snapshot from one pool to another one?


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