[Gluster-devel] Is it possible to setup a RAID 6 using GlusterFS?

[Pascal]

Hello David,

I hope that you will read this, even though your post was written some
days ago.

I was trying to configure your suggestion "with a replica count of 3"
and I wasn't able to do it. 


My original setup with four nodes: node1, node2, node3, node4.

# gluster volume create gluster-storage replica 2 transport tcp
ip-node1:/data ip-node2:/data ip-node3:/data ip-node4:/data

The result:
Node1 and node2 replicated the files among each other and node3 and
node4 did the same. The replication group of node1 and node2 (group1)
distributed the files among the replication group of node3 and node4
(group2). 

The problem:
Two hard drives could fail at the same time, but just one hard drive
from each replication group. My aim is to archive something were any two
hard drives could fail.


Trying to setup a replica count of 3 with my four nodes:

# gluster volume create gluster-storage replica 3 transport tcp
ip-node1:/data ip-node2:/data ip-node3:/data ip-node4:/data
> number of bricks is not a multiple of replica count

This means to my, that I would need six nodes/bricks and that would
lead me to the same situation as before. Node1, node2 and node3 would
build a replication group and node4, node5 and node6 would build the
other replication group and both groups together would save all the
data. 
I would still have the problem that two hard drives from one
replication group weren't allowed to fail at the same time.


Did I misunderstood your idea of a "replica count of 3"? Would you be
so kind to explain it to me?

Thanks in advance!

Pascal


Am Thu, 29 Mar 2012 10:47:38 -0400
schrieb David Coulson <david at davidcoulson.net>:

> Try doing a distributed-replica with a replica count of 3. Not really 
> 'RAID-6' comparable, but you can have two nodes fail without outage.
> 
> http://download.gluster.com/pub/gluster/glusterfs/3.2/Documentation/AG/html/sect-Administration_Guide--Setting_Volumes-Distributed_Replicated.html
> 
> On 3/29/12 10:39 AM, Pascal wrote:
> > Hello everyone,
> >
> > I would like to know if it is possible to setup a GlusterFS
> > installation which is comparable to a RAID 6? I did some research in
> > the community and several mailing lists and all I could find were
> > the similar request from 2009
> > (http://gluster.org/pipermail/gluster-users/2009-May/002208.html,
> > http://www.gluster.org/community/documentation/index.ph/Talk:GlusterFS_Roadmap_Suggestions).
> >
> > I would just like to have a scenario where two GlusterFS
> > nodes/servers, respectively their hard drives, could fail at the
> > same time.
> >
> > Thanks in advance!
> > Pascal
> >
> >
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