Gluster users - Jul 2017 - Replicated volume, one slow brick

I have been trying to figure out how glusterfs-fuse client will handle it
when 1 of 3 bricks in a 3-way replica is slower than the others.

It looks like a glusterfs-fuse client will send requests to all 3 bricks
when accessing a file. But what happens when one of the bricks is not
responding in time?

We saw an issue when we added external load to the raid volume where the
brick was located. The disk became 100% busy, and as a result the
glusterfs-clients hang when they access the volume.

Is there a way to avoid this, and make the clients ask the other two bricks
for the data when one brick is too slow?

Thanks

?yvind Krosby
SRE, Zedge.net
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You won't have 3x copies of data but you could try replica2 + arbiter
volume?  Other than that I am not sure how to or if its possible to compensate
for a slow brick like that.

-b

----- Original Message -----
> From: "?yvind Krosby" <oyvind at zedge.net>
> To: gluster-users at gluster.org
> Sent: Thursday, July 13, 2017 4:44:09 AM
> Subject: [Gluster-users] Replicated volume, one slow brick
> 
> I have been trying to figure out how glusterfs-fuse client will handle it
> when 1 of 3 bricks in a 3-way replica is slower than the others.
> 
> It looks like a glusterfs-fuse client will send requests to all 3 bricks
when
> accessing a file. But what happens when one of the bricks is not responding
> in time?
> 
> We saw an issue when we added external load to the raid volume where the
> brick was located. The disk became 100% busy, and as a result the
> glusterfs-clients hang when they access the volume.
> 
> Is there a way to avoid this, and make the clients ask the other two bricks
> for the data when one brick is too slow?
> 
> Thanks
> 
> ?yvind Krosby
> SRE, Zedge.net
> 
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://lists.gluster.org/mailman/listinfo/gluster-users

Adding gluster-devel

Raghavendra,
     I remember we discussing about handling these kinds of errors by
ping-timer expiry? I may have missed the final decision on how this was
decided to be handled. So asking you again ;-)

On Thu, Jul 13, 2017 at 2:14 PM, ?yvind Krosby <oyvind at zedge.net>
wrote:
> I have been trying to figure out how glusterfs-fuse client will handle it
> when 1 of 3 bricks in a 3-way replica is slower than the others.
>
> It looks like a glusterfs-fuse client will send requests to all 3 bricks
> when accessing a file. But what happens when one of the bricks is not
> responding in time?
>
> We saw an issue when we added external load to the raid volume where the
> brick was located. The disk became 100% busy, and as a result the
> glusterfs-clients hang when they access the volume.
>
> Is there a way to avoid this, and make the clients ask the other two
> bricks for the data when one brick is too slow?
>
> Thanks
>
> ?yvind Krosby
> SRE, Zedge.net
>
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://lists.gluster.org/mailman/listinfo/gluster-users
>


-- 
Pranith
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