[Gluster-users] Unify namespace re-creation (Was: No space left on device...)

[Krzysztof Strasburger]

On Tue, Apr 06, 2010 at 06:47:43PM +0800, Kali Hernandez wrote:
> 
> 
> Well, let's say I changed my mind about the namespace node(s) after I 
> had started moving a lot of data. In my case, I have dedicated 2 full 
> nodes (which is quite useless) as namespace nodes.
> 
> After realizing I did wrong, I want delete my namespace data from those 
> nodes, and add their storage space to the cluster. I would delete the 
> zero-sized files stored on those nodes, and then add them in the client 
> config as 2 nodes mirrored, later aggregated in the unify config.
> 
> As I will need to have some namespace node config for unify, I add 
> another brick-ns config on the server side on those 2 nodes, and I set 
> the client volume to use the new brick-ns's (replicated) as namespace on 
> my unify. But the info here is empty, so Unify will not be able to find 
> any file.
> 
> Is there any way so I can re-create all the namespace info?
> 
> Would it work if I just move (when both client and servers are down) the 
> info from the current brick to the newly created brick-ns storage folder?
IMHO it will work, but do not change file modification times in the 
namespace. Try to umount the unify volume, mount the old and new namespace
(as replicated volumes) separately and cp -a (safer, as you may return back
to the old namespace, if something goes the wrong way) or mv should do the rest.
Then change the namespace volume in config files, mount the unified volume
and see, whether it works. 
> 
> Can I freely add new nodes to the Unify'ed gluster? I am using ALU 
> scheduler.
I didn't try that, but nothing prevents you. Do not forget to stop glusterfs
first and update the client config files on all nodes, before you start
to use the new setup. Unify has some nice features, which DHT in its present
form doesn't have.
Krzysztof