Gluster users - May 2018 - arbiter node on client?

is possible to add an arbiter node on the client?

Let's assume a gluster storage made with 2 storage server. This is prone to
split-brains.
An arbiter node can be added, but can I put the arbiter on one of the
client ?

Can I use multiple arbiter for the same volume ? In example, one arbiter on
each client.

On Sun, May 06, 2018 at 11:15:32AM +0000, Gandalf Corvotempesta
wrote:
> is possible to add an arbiter node on the client?
I've been running in that configuration for a couple months now with no
problems.  I have 6 data + 3 arbiter bricks hosting VM disk images and
all three of my arbiter bricks are on one of the kvm hosts.
> Can I use multiple arbiter for the same volume ? In example, one arbiter on
> each client.
I'm pretty sure that you can only have one arbiter per subvolume, and
I'm not even sure what the point of multiple arbiters over the same data
would be.

In my case, I have three subvolumes (three replica pairs), which means I
need three arbiters and those could be spread across multiple nodes, of
course, but I don't think saying "I want 12 arbiters instead of
3!"
would be supported.

-- 
Dave Sherohman

Il giorno lun 7 mag 2018 alle ore 13:22 Dave Sherohman <dave at
sherohman.org>
ha scritto:
> I'm pretty sure that you can only have one arbiter per subvolume, and
> I'm not even sure what the point of multiple arbiters over the same
data
> would be.
Multiple arbiter add availability. I can safely shutdown one hypervisor
node (where arbiter is located)
and still have a 100% working cluster with quorum.

Is possible to add arbiter on the fly or must be configured during the
volume creation ?

One thing to remember with arbiters is that they need IOPs, not capacity as
much.  With a VM use case this is less impactful, but workloads with lots of
smallfiles can become heavily bottlenecked at the arbiter.  Arbiters only save
metadata, not data, but metadata needs lots of small reads and writes.  I have
seen many instances where the the arbiter had considerably less IOPs than the
other bricks and it lead to perf issues.  With VMs you don't have thousands
of files so its prolly not a big deal, but in more general purpose workloads its
important to remember this.

HTH!

-b

----- Original Message -----
> From: "Dave Sherohman" <dave at sherohman.org>
> To: gluster-users at gluster.org
> Sent: Monday, May 7, 2018 7:21:49 AM
> Subject: Re: [Gluster-users] arbiter node on client?
> 
> On Sun, May 06, 2018 at 11:15:32AM +0000, Gandalf Corvotempesta wrote:
> > is possible to add an arbiter node on the client?
> 
> I've been running in that configuration for a couple months now with no
> problems.  I have 6 data + 3 arbiter bricks hosting VM disk images and
> all three of my arbiter bricks are on one of the kvm hosts.
> 
> > Can I use multiple arbiter for the same volume ? In example, one
arbiter on
> > each client.
> 
> I'm pretty sure that you can only have one arbiter per subvolume, and
> I'm not even sure what the point of multiple arbiters over the same
data
> would be.
> 
> In my case, I have three subvolumes (three replica pairs), which means I
> need three arbiters and those could be spread across multiple nodes, of
> course, but I don't think saying "I want 12 arbiters instead of
3!"
> would be supported.
> 
> --
> Dave Sherohman
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