incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ryan Hadley <r...@sgizmo.com>
Subject Inconsistent data issues when running nodetool move.
Date Fri, 13 May 2011 22:05:40 GMT
Hi,

I'm running Cassandra (0.7.4) on a 4 node ring.  It was a 3 node ring, but we ended up expanding
it to 4... So then I followed the many suggestions to rebalance the ring.  I found a script
that suggested I use:

# ~/nodes_calc.py 
How many nodes are in your cluster? 4
node 0: 0
node 1: 42535295865117307932921825928971026432
node 2: 85070591730234615865843651857942052864
node 3: 127605887595351923798765477786913079296

So I started to migrate each node to those tokens.

I have my replication factor set to 2, so I guess I was expecting to be able to continue to
use this ring without issues.  But it seems that the node still accepts writes while it's
decommissioning?  I say this because if I interrupt the decommission by stopping Cassandra
and starting it again, it appears to run through several commit logs.  And as soon as it's
through with those commit logs, I no longer get consistency issues.

The issue I'm seeing is that writes to this ring will succeed, but it's possible for a subsequent
read to return an older object.  For several minutes even.

I'm not sure if I did something wrong... learning as I go here and this list archive has been
very useful.  But, is there anyway I can rebalance the node and get better consistency?

Thanks,
Ryan
Mime
View raw message