[Gluster-users] Feedback and Questions on afr+unify

Prabhu Ramachandran prabhu at aero.iitb.ac.in
Thu Dec 18 04:05:30 UTC 2008


I just installed and configured a couple of machines with glusterfs 
(1.4.0-rc3).  It seems to work great.  Thanks for the amazing software.! 
I've been looking for something like this for years.

I have some feedback and questions.  My configuration is a bit 
complicated.  I have two machines each with two disks and each of which 
with two partitions that I wanted to use (i.e. 8 partitions across 4 
disks on 2 machines).  I wanted to expose one single unified filesystem 
spanning 4 partitions on each machine and have these replicated via afr 
on each machine for high availability. The machines are two desktops 
connected on a 10Mbps network.

I exposed the individual partitions, unified them and then the client 
volfile simply afr'd these two.  Attached are the volfiles for 
reference.  Here is some feedback:

  - This one is very minor. It wasn't explicitly clear from the docs 
that to use unify one needed (a) locking and (b) the namespace.  The 
place this is mentioned is in "Understanding unify translator" which 
isn't the first place a user would look.  Would be nice if this were 
mentioned somewhere.

  - There are a lot of options to choose from and without Anands initial 
help in person I would be lost trying to choose a scheduler.  It would 
be great if there were some recommended solutions.  I understand the 
software is rapidly growing but this would make life easier for new 

  - One of my servers is behind a router with NAT enabled and this 
caused problems.  I kept getting errors of this kind when trying to 
connect from the NATed client ( to the other one.  The logfile 
gave me the following:

2008-12-18 00:25:40 E [addr.c:117:gf_auth] auth/addr: client is bound to 
port 59327 which is not privilaged
2008-12-18 00:25:40 E [authenticate.c:193:gf_authenticate] auth: no 
authentication module is interested in accepting remote-client
2008-12-18 00:25:40 E [server-protocol.c:6842:mop_setvolume] server: 
Cannot authenticate client from

  I worked around this problem by exposing the machine as a DMZ host 
from the router but this is not ideal.  Is there something I can do to 
fix this?

  - The archives of the list are categorized for each day 
(http://gluster.org/pipermail/gluster-users/).  This is quite 
inconvenient.  It would be much more convenient if this were done for 
each month.

In addition I have a few questions:

  - What would happen if I change the scheduler to something else? 
Would that hose the data?  I haven't moved all my data yet so I can 
experiment currently.  I am not likely to tinker with the setup later on 
though since this will contain important data.

  - What scheduler should I consider using?  Anand suggested keeping it 
simple and start with rr.  Should this be fine for my needs or would it 
be better to use hash or alu?

  - What would happen if I added another brick, say another disk to the 
existing set on one of the machines?  Would it break the round-robin 
scheduler that I am using?  I see from the FAQ that this should work 
with the alu but will it work with rr?

Many thanks once again for the awesome clustered file system!

Prabhu Ramachandran                 http://www.aero.iitb.ac.in/~prabhu
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