[Gluster-users] gluster and multipath

Alessandro Briosi
Tue, 24 Jan 2017 12:23:18 -0000

Il 24/01/2017 12:09, Lindsay Mathieson ha scritto:
> On 24/01/2017 6:33 PM, Alessandro Briosi wrote:
>> I'm in the process of creating a 3 server cluster, and use gluster
as a
>> shared storage between the 3.
>
> Exactly what I run - my three gluster nodes are also VM Servers
> (Proxmox cluster);
>
>
Ok, I also am going to use Proxmox. Any advise on how to configure the
bricks?
I plan to have a 2 node replica. Would appreciate you sharing your full
setup :-)

>> I have 2 switches and each server has a 4 ethernet card which I'd
like
>> to dedicate to the storage.
>>
>> For redundancy I thought I could use multipath with gluster (like with
>> iscsi), but am not sure it can be done.
>
>
> I don't think so and there isn't really a need for it. Each node in
a
> gluster cluster is an active server, there is no SPOF. A gluster
> client (fuse or gfapi) when connecting to the cluster will download
> the list of all servers. If the server it is connected to dies, it
> will failover to another server. I have done this many times with
> rolling live upgrades. Additionally you can specify a list of servers
> for the initial connection.
>
>
Ok, the only thing I want to avoid is if the switch goes down. This is a
SPOF.
Having 2 switches would allow me to maintain 1 switch while let the
other handle the cluster.

>> So the question is:
>> can I use dm-multipath with gluster
>
> Probably not.
>
>> If not should I use nic bonding?
>
> Yes, balance-alb is recommenced. With three servers 2 dedicated nics
> per server is optimal, I doubt you would get much benefit from 3 or 4
> nics except redundancy. With 2*1G nics I get a reliable 120 MB/s seq
> writes.
Ok so having 2 bonds 1 attached to each switch would work. Though I
still cannot get how to make gluster use both links (or at least one
with active/passive).
Should I work on RRDNS and keepalived? Or use some bonding of a bond
within the 2 switches with balance-rr in this case?
How do other implement this?

>
> I experimented with balance-rr and got somewhat erratic results.
>
>> Is there a way to have it use 2 bonded interfaces (so if 1 switch goes
>> down, the other takes up or better use both for maximal throughput)?
>
> I'm pretty sure you could bond 4 nics with 2 through 1 switch and 2
> through the others. That should keep working if a switch goes down.
>
Well I was going to use LACP which seems to be the best once configured,
needs switch support, but that's not a problem.

Thanks.
Alessandro

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