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From A J <s5a...@gmail.com>
Subject Re: Clock skew
Date Tue, 28 Jun 2011 18:56:33 GMT
Thanks.

On Tue, Jun 28, 2011 at 1:31 PM, Dominic Williams
<dwilliams@system7.co.uk> wrote:
> Hi, yes you are correct, and this is a potential problem.
> IMPORTANT: If you need to serialize writes from your application servers,
> for example using distributed locking, then before releasing locks you must
> sleep for a period equal to the maximum variance between the clocks on your
> application server nodes.
> I had a problem with the clocks on my nodes which led to all kinds of
> problems. There is a slightly out of date post, which may not mentioned the
> above point, on my experiences
> here http://ria101.wordpress.com/2011/02/08/cassandra-the-importance-of-system-clocks-avoiding-oom-and-how-to-escape-oom-meltdown/
> Hope this helps
> Dominic
> On 27 June 2011 23:03, A J <s5alye@gmail.com> wrote:
>>
>> During writes, the timestamp field in the column is the system-time of
>> that node (correct me if that is not the case and the system-time of
>> the co-ordinator is what gets applied to all the replicas).
>> During reads, the latest write wins.
>>
>> What if there is a clock skew ? It could lead to a stale write
>> over-riding the actual latest write, just because the clock of that
>> node is ahead of the other node. Right ?
>
>

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