[Gluster-users] Gluster FS replication

[Haris Zukanovic]

Hi everyone,

I am using Gluster in replication mode.
Have 3 bricks on 3 different physical servers connected with WAN. This 
makes writing but also reading files from Gluster mounted volume very slow.
To remedy this I have made my web application read Gluster files from 
the brick directly (I make a readonly bind mount of the brick), but 
write to the Gluster FS mounted volume so that the files will instantly 
replicate on all 3 servers. At least, "instant replication" is what I 
envision GLuster will do for me :)

My problem is that files sometimes do not replicate to all 3 servers 
instantly. There are certainly short network outages which may prevent 
instant replication and I have situations like this:

ssh web1-prod ls -l 
/home/gluster/r/production/zdrava.tv/web/uploads/24/playlist/38/19_10_2012_18.js
-rw-r--r-- 1 apache apache 75901 Oct 19 18:00 
/home/gluster/r/production/zdrava.tv/web/uploads/24/playlist/38/19_10_2012_18.js
web2-prod.
ssh web2-prod ls -l 
/home/gluster/r/production/zdrava.tv/web/uploads/24/playlist/38/19_10_2012_18.js
-rw-r--r-- 1 apache apache 0 Oct 19 18:00 
/home/gluster/r/production/zdrava.tv/web/uploads/24/playlist/38/19_10_2012_18.js
web3-prod.
ssh web3-prod ls -l 
/home/gluster/r/production/zdrava.tv/web/uploads/24/playlist/38/19_10_2012_18.js
-rw-r--r--. 1 apache apache 75901 Oct 19 18:00 
/home/gluster/r/production/zdrava.tv/web/uploads/24/playlist/38/19_10_2012_18.js

Where the file on web2 server brick has a size of 0. So serving this 
file from web2 makes my application make errors..

I have had a brain-split situation couple of times and resolved 
manually. The above kind of situation is not a brain-split and resolves 
and (re-)replicates completly with a simple "ls -l" on the file in 
question from any of the servers.

My question is:
I suppose that the problem here is incomplete replication for the file 
in question due to temporary network problems.
How to insure the complete replication immediatly after the network has 
been restored?


kind regards
Haris Zukanovic

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Haris Zukanovic