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From Maki Watanabe <watanabe.m...@gmail.com>
Subject Re: Inconsistent data issues when running nodetool move.
Date Sat, 14 May 2011 14:24:45 GMT
If you do CL=ONE write + CL=ALL read, then it seems OK...
You should better to stay in this thread until some of experts would
answer your question.

2011/5/14 Ryan Hadley <ryan@sgizmo.com>:
> Thanks Maki,
>
> That makes sense with my symptoms...  I was doing a CL=ONE for write and a CL=ALL for
read, expecting that to be sufficient.
>
> I will try both set to ALL and see if I get better consistency.
>
> -Ryan
>
> On May 14, 2011, at 4:41 AM, Maki Watanabe wrote:
>
>> It depends on what you really use which CL for your operations.
>> Your RF is 2, so if you read/write with CL=ALL, your r/w will be
>> always consistent. If your read is CL=ONE, you have chance to read old
>> data anytime, decommission is not matter. CL=QUORUM on RF=2 is
>> semantically identical with CL=ALL.
>>
>> maki
>>
>> 2011/5/13 Ryan Hadley <ryan@sgizmo.com>:
>>> 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
>
>



-- 
w3m

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