GEOM: mirroring and journaling

Adam Vande More amvandemore at
Tue Jul 27 16:41:52 UTC 2010

On Tue, Jul 27, 2010 at 11:10 AM, Joey Mingrone <joey at> wrote:

> Hello,
> I'm attempting to set up a storage server with mirrored and journaled
> filesystems.  Initially I did the following:
> sysctl kern.geom.debugflags=17
> dd if=/dev/zero of=/dev/ad8 bs=1k count=1
> dd if=/dev/zero of=/dev/ad10 bs=1k count=1
> gmirror label -vb round-robin gm0 /dev/ad8
> gmirror load
> gjournal label /dev/mirror/gm0
> gjournal load
> newfs -O 2 -J /dev/mirror/gm0.journal
> mount /dev/mirror/gm0.journal /mnt/mirror2
> gmirror insert gm0 /dev/ad10
> ,but I read in the archives there are potential issues with the
> labelling.  Does anyone have any suggestions (or references to
> documentation) describing how this could be done?
> Are the GEOM parts for doing this sufficiently mature to consider this
> safe?  This did seem to be working, but when I did a dump I got kernel
> panics like others who have posted recently.

Sure it's safe, but you should hardcode the metadata, see man gjournal(8)

You should also read the section on the size of the journal, I'd guess yours
is too small and the source of your panics.

Adam Vande More

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