How to mirror a geli partition?

R. B. Riddick arne_woerner at
Thu Jan 11 17:28:03 UTC 2007

--- Christian Baer <christian.baer at> wrote:
> 1st
> The mirrored partitions will contain the same date (naturally) but the
> drives however will not. It this a problem? Meaning that the mirrored
> partitions
> on drive0 and drive1 will probably habe different positions on their
> drives.
Nope. Since GEOM providers can be consumers, and since partitions, slices and
disks are GEOM providers, too, there will be no such prob...

> 2nd
> The gmirror manpage only uses full drives as providers in its examples.
> I am guessing that I could also use a partition as a provider like
> /dev/ad0s1d. Did I guess that right?
See above... Slices, partitions can be used like disks regarding
GEOM-consumer-able-lish-ness... :-)

> 3rd
> What happens if the partitions aren't exactly the same size? This could
> happen if the partitions have different positions on the drive and I
> specify the size in MB or GB. I don't care if I lose a bit of room
> (meaning that the size of the smaller partition is the one that counts).
> I'm just a little worried that a rounding error that makes partition0 a
> few blocks larger than partition1 could cause problems.
gmirror will build the minimum, if I recall the code correctly... At least in
verbose mode gmirror will tell u how much u r wasting, IIRC...

> 4th
> This is actually the biggest problem I am facing. In what order do I do
> this? I was thinking along this way:
> 1 - Create partions and try to get them the same size. :-)
> 2 - Fill one (or both?) with random data.
> 3 - Make a geli provider out of one of them, newfs it.
> 4 - Do something like 'gmirror label -v -b load secret 1.eli'
>     and 'gmirror insert 2.eli'
> I am not sure if I should reverse the order of 3 and 4. Or have I gotten
> the whole idea wrong?
I would do the gmirror first and then the geli on top of the gmirror, as if the
gmirror was a normal disk/partition/slice or whatever u r used to...

> Can someone point me in the right direction?
Hope I did...


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