Dear Ashish,

thank you very much for your support.
I think that I’m not able to change the volume configuration for the reason you 
mentioned at the end of your n.1 answer.
GNFS mount is a very good idea, thank you!!! I will use it in my action plan.

I’m very happy to have been helped by you (Ashish and Serkan).
Regards,
Mauro

> Il giorno 07 giu 2018, alle ore 16:49, Ashish Pandey <[email protected]> ha 
> scritto:
> 
> Mauro,
> 
> Your plan looks fine to me. However, I would like to add few points.
> 
> 1 - After adding 3 more nodes you will have overall 6 nodes. It would be 
> better if you can have 1 brick on each server for any EC subvolume.
>      For example: for 4+2, all 6 bricks should be on different nodes. This 
> will help you to have better redundancy. For example even if 2 nodes go down, 
> you will still have 4 good bricks.
>      In your existing setup, if 2 nodes go down you will loose 4 bricks which 
> will make the volume unusable.
>      Although it would be tricky to do so, as you have older version on 3 
> nodes and newer on 3 nodes.
> 
> 2 - In your plan, if you can use gnfs mount, you could easily copy the data 
> from one volume to other. In this case the client would be running on one of 
> the server which would be same as the server version.
> 
> 3 - The plan you mentioned will also work. However, you have to have *older* 
> client version on third machine on which you are going to mount both volumes.
> 
> 4 - The plan which Serkan mentioned is also a feasible plan specially if IO's 
> are not going on. However, just keep the first point in your mind and see if 
> you can reach to that setup.
> 
> ---
> Ashish
> 
> 
> 
> 
> 
> From: "Serkan Çoban" <[email protected]>
> To: "Mauro Tridici" <[email protected]>
> Cc: "Gluster Users" <[email protected]>
> Sent: Thursday, June 7, 2018 7:19:50 PM
> Subject: Re: [Gluster-users] Expanding a distributed disperse volume: some 
> questions about the action plan
> 
> >in order to copy the data from the old volume to the new one, I need a third 
> >machine that can mount both the volumes; it's possible? if yes, which 
> >gluster client version should I use/install on the "bridge" machine?
> Yes it is possible, you need to install old client version to bridge
> server, old clients can talk to new servers
> 
> Why not just extend the old cluster & rebalance and then upgrade to
> latest version of glusterfs?
> 
> On Thu, Jun 7, 2018 at 3:18 PM, Mauro Tridici <[email protected]> wrote:
> > Dear Users,
> >
> > just one year ago, we implemented a tier2 storage based on GlusterFS
> > v.3.10.5 and we can say that it works like a charm.
> > The GlusterFS volume has been created using 3 physical servers (each server
> > contains 12 disks, 1 brick per disk).
> >
> > Below, you can find some information about the gluster volume type
> >
> > Volume Name: tier2
> > Type: Distributed-Disperse
> > Volume ID: a28d88c5-3295-4e35-98d4-210b3af9358c
> > Status: Started
> > Snapshot Count: 0
> > Number of Bricks: 6 x (4 + 2) = 36
> > Transport-type: tcp
> >
> > Now, it's time to expand this volume so we bought 3 new servers similar to
> > the 3 existing servers. Since we would like to upgrade the Gluster version
> > to last available one, we would like to know if the following action plan is
> > correct and safe:
> >
> > 1) creation of a new gluster distributed disperse volume (6x(4+2)) using the
> > 3 new servers and the new gluster version;
> > 2) copy of all the data saved on the old gluster volume to the new one;
> > 3) complete erasure of three old servers operating system;
> > 4) installation of the last available version of the operating system and
> > glusterfs software stack on the three old servers;
> > 5) expansion of the volume (created at point nr.1) adding the new bricks
> > (created at point nr.4)
> >
> > If our action plan can be considered "validated", I have an other question:
> >
> > - in order to copy the data from the old volume to the new one, I need a
> > third machine that can mount both the volumes; it's possible? if yes, which
> > gluster client version should I use/install on the "bridge" machine?
> >
> > Thank you very much for your attention.
> > Regards,
> > Mauro
> >
> >
> > _______________________________________________
> > Gluster-users mailing list
> > [email protected]
> > http://lists.gluster.org/mailman/listinfo/gluster-users
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