[Linux-cluster] GFS and CLVM-snapshot

[David Teigland]

On Mon, May 09, 2005 at 05:04:37AM +0900, Kenji Wakamiya wrote:
> Hello,
> 
> I have some basic questions.
> I'm using GFS with the following configuration.
> 
>   node1  node2  node3 (FC3)
>    GFS    GFS    GFS
>    LV     LV     LV   <-- CLVM
>   GNBD   GNBD   GNBD  <-- gnbd_import -n
>    |      |      |
>    +------+------+
>           |
>          GNBD  <-- gnbd_serv -n / gnbd_export -c
>          node0 (file server: FC3)
> 
> Only for snapshot and backup, CLVM has been introduced here.
> Is a setup such as this correct?
> If so (or not :), why "sometimes" the following error occor?
> Don't I need freeze/unfreeze GFS manually, like XFS?

CLVM snapshots do not work with GFS, sorry.  Maybe sometime in the future.
However, this should be possible:

   node1  node2  node3 (FC3)
    GFS    GFS    GFS
   GNBD   GNBD   GNBD  <-- gnbd_import -n
    |      |      |
    +------+------+
           |
          GNBD  <-- gnbd_serv -n / gnbd_export -c
          LV    <-- LVM2
          node0 (file server: FC3)
 
In this case you should run:

node1-3# gfs_tool freeze /mnt/gfs
node0#   lvcreate -s -n lv0ss0 ...
node1-3# gfs_tool unfreeze /mnt/gfs
node0#   gnbd_export -c -d lv0ss0 -n nbd0ss0
node1#   gnbd_import -n -i node0
node1#   mount -t gfs -o ro,lockproto=lock_nolock /dev/gnbd/nbd0ss0

I've not tried this myself, but I don't think there's anything wrong with
it in principle.

Dave