[Gluster-users] Reconfiguring volume type

[Rahul C S]

Hi Udo,

For your first question, the answer right now is No and so you cannot change a volume type from distributed to distributed-replicate with gluster 3.1.2 online. 

You would have to delete the volume and create a new volume with type distribute replicate using:
$ gluster volume create <VOLNAME> replica 2 <brick1> <brick2> <brick3> <brick4> 
(A volume must have 4 bricks to become a distributed-replicate volume)

However if you have a replicate volume with count 2 already created, then you just need to add 2 more bricks and it will automatically become a distributed replicate volume.
This can be scaled to 6 bricks by adding 2 more bricks again and these steps can be done when the volume is online itself.

For the last question,
"remove-brick" command does not migrate data, the data in that brick cannot be accessed from the client unlike "replace-brick" which actually migrates data from one brick to the another.


----- Original Message -----
From: "Udo Waechter" <udo.waechter at uni-osnabrueck.de>
To: gluster-users at gluster.org
Sent: Tuesday, February 15, 2011 11:23:39 PM
Subject: [Gluster-users] Reconfiguring volume type

Hi all.
I have been looking around the web but did not find a satisfying answer.
Is it possible to change a volume type from distributed to distributed+replica with gluster 3.1.2?
An online way at least?

The manpage suggests that I can do:
$ gluster volume add-brick <VOLNAME> [(replica <COUNT>)|(stripe <COUNT>)] <NEW-BRICK> ...

I tried to add additional bricks to an existing distribute-type volume by:
gluster volume add-brick testvol replica 2 <newbrick>

This failed.

I have 3 bricks in a distribute volume and would like to add additional 3 bricks to have it distribute+replicate.


I can do it offline by (something like):
- stop the volume
- delete it
- recreate it with addtional replicate bricks.

I guess i need to take care that the data from the bricks is somehow synched to just one or so...

Last small question: If I "gluster remove-brick" one brick, does its data get migrated to the other bricks? This is the case with "replace-brick".

Thanks for your time and thoughts,
udo.

-- 
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-- 
regards,
Rahul