Gluster users - Jun 2013 - Distributed-replicate across four bricks with two hosts

Hi,

I created a distributed-replicated volume across two servers and two bricks
each.  Here is the configuration:

Volume Name: slice1
Type: Distributed-Replicate
Status: Started
Number of Bricks: 2 x 2 = 4
Transport-type: tcp
Bricks:
Brick1: elkpinfkvm05-bus:/srv/brick1
Brick2: elkpinfkvm05-bus:/srv/brick2
Brick3: elkpinfkvm06-bus:/srv/brick1
Brick4: elkpinfkvm06-bus:/srv/brick2

So naturally the question comes up: how do I know the replication is
happening across the hosts, not two bricks on the same host?  If one of the
hosts went down, I want to make sure the storage is still available.
 Thanks,

Ziemowit
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On Fri, Jun 14, 2013 at 4:35 PM, Ziemowit Pierzycki
<ziemowit at pierzycki.com> wrote:
> Hi,
>
> I created a distributed-replicated volume across two servers and two bricks
> each.  Here is the configuration:
>
> Volume Name: slice1
> Type: Distributed-Replicate
> Status: Started
> Number of Bricks: 2 x 2 = 4
> Transport-type: tcp
> Bricks:
> Brick1: elkpinfkvm05-bus:/srv/brick1
> Brick2: elkpinfkvm05-bus:/srv/brick2
> Brick3: elkpinfkvm06-bus:/srv/brick1
> Brick4: elkpinfkvm06-bus:/srv/brick2
>
> So naturally the question comes up: how do I know the replication is
> happening across the hosts, not two bricks on the same host?  If one of the
> hosts went down, I want to make sure the storage is still available.
> Thanks,
Test it of course by taking down different nodes!
>
> Ziemowit
>
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://supercolony.gluster.org/mailman/listinfo/gluster-users

On 06/14/13 13:35, Ziemowit Pierzycki wrote:
> Hi,
>
> I created a distributed-replicated volume across two servers and two
> bricks each.  Here is the configuration:
>
> Volume Name: slice1
> Type: Distributed-Replicate
> Status: Started
> Number of Bricks: 2 x 2 = 4
> Transport-type: tcp
> Bricks:
> Brick1: elkpinfkvm05-bus:/srv/brick1
> Brick2: elkpinfkvm05-bus:/srv/brick2
> Brick3: elkpinfkvm06-bus:/srv/brick1
> Brick4: elkpinfkvm06-bus:/srv/brick2
>
> So naturally the question comes up: how do I know the replication is
> happening across the hosts, not two bricks on the same host?  If one of
> the hosts went down, I want to make sure the storage is still available.
Replica sets are done in order that the bricks are added to the volume.
So, you have the replica set size set to 2, which means every 2 bricks 
are mirrored, down the line.

Brick1 + Brick2 = Replica 1
Brick3 + Brick4 = Replica 2

Then the distribution (DHT) distributes files over Replica 1 and Replica 2.

So, you have an issue here, that both bricks of a replica set are on the 
same host.

-- 
Mr. Flibble
King of the Potato People