[Gluster-users] Add single server

[Joe Julian]

On 05/01/2017 11:55 AM, Pranith Kumar Karampuri wrote:
>
>
> On Tue, May 2, 2017 at 12:20 AM, Gandalf Corvotempesta 
> <gandalf.corvotempesta at gmail.com 
> <mailto:gandalf.corvotempesta at gmail.com>> wrote:
>
>     2017-05-01 20:43 GMT+02:00 Shyam <srangana at redhat.com
>     <mailto:srangana at redhat.com>>:
>     > I do agree that for the duration a brick is replaced its
>     replication count
>     > is down by 1, is that your concern? In which case I do note that
>     without (a)
>     > above, availability is at risk during the operation. Which needs
>     other
>     > strategies/changes to ensure tolerance to errors/faults.
>
>     Oh, yes, i've forgot this too.
>
>     I don't know Ceph, but Lizard, when moving chunks across the cluster,
>     does a copy, not a movement
>     During the whole operation you'll end with some files/chunks
>     replicated more than the requirement.
>
>
> Replace-brick as a command is implemented with the goal of replacing a 
> disk that went bad. So the availability was already less. In 2013-2014 
> I proposed that we do it by adding brick to just the replica set and 
> increase its replica-count just for that set once heal is complete we 
> could remove this brick. But at the point I didn't see any benefit to 
> that approach, because availability was already down by 1. But with 
> all of this discussion it seems like a good time to revive this idea. 
> I saw that Shyam suggested the same in the PR he mentioned before.

I've always been against the idea of being a replica down based on that 
supposition. I've never had to replace-brick because a brick failed. 
It's always been for reconfiguration reasons. Good monitoring and 
analysis can predict drive failures in plenty of time to replace a 
functioning brick.

>
>     If you have a replica 3, during the movement, some file get replica 4
>     In Gluster the same operation will bring you replica 2.
>
>     IMHO, this isn't a viable/reliable solution
>
>     Any change to change "replace-brick" to increase the replica count
>     during the operation ?
>
> It can be done. We just need to find time to do this.
>
>
> -- 
> Pranith
>
>
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