gmirror, gjournal and glabel - which order?

Manolis Kiagias sonicy at
Mon Oct 12 22:08:49 UTC 2009

Daniel Bye wrote:
> Hi all,
> I'm having a hard time trying to work out which order I should set up
> gmirror, glabel and gjournal on a new system. I want to journal my
> /home partition, label all the partitions for ease of reference, and
> use gmirror to save me in the event a disk goes bad. I am struggling
> to fit the pieces together conceptually in my mind. I understand the
> processes involved in setting each part separately - my problem is in
> trying to build this up in the right order so that it all makes sense.
> So far, I have labelled the primary drive and set up the journal. I have
> edited fstab to reflect the labels and journalled file system on /home.
> If I now build a mirror, don't I need to alter fstab to mount that and
> not the stuff in /dev/label? In which case, I guess I need to build the
> mirror first, and then set up labels and journals?
> I'm going round and round in circles here and none of the stuff I've
> read on the web enlightens me... :-/
> Any insights or suggestions would be taken as a great kindness!
> Dan
When not mirroring,  I first create the journals and then label the
resulting adxxxx.journal devices
In case you are doing a gmirror device, you would not really need the
separate label step - the gm device name won't change and gmirror is not
affected if the device names of the individual disks change (the disks
are marked as part of a mirror and scanned at startup).
When you are creating the composite gmirror device you are effectively
labeling it anyway i.e. gmirror label gm0...
Now if you follow the usual tutorials found in the web you would be
using gm0 / gm1 but you actually name it any way you wish.
If you really need to label the separate gmirrored partitions, do it
after setting up the mirror.

Concerning the order of journals and mirroring, I  create the journals
first, then mirror the result. This has always worked fine for me.

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