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From Yan Chunlu <springri...@gmail.com>
Subject Re: how to know if nodetool cleanup is safe?
Date Thu, 25 Aug 2011 03:38:12 GMT
got it! thanks a lot for the explanation!

On Wed, Aug 24, 2011 at 1:06 AM, Edward Capriolo <edlinuxguru@gmail.com>wrote:

>
> On Tue, Aug 23, 2011 at 11:56 AM, Sam Overton <soverton@acunu.com> wrote:
>
>> On 21 August 2011 12:34, Yan Chunlu <springrider@gmail.com> wrote:
>>
>>> since "nodetool cleanup" could remove hinted handoff,  will it cause the
>>> data loss?
>>
>>
>> Hi Yan,
>>
>> Hints are not guaranteed to be delivered and "nodetool cleanup" is one of
>> the reasons for that. This will only cause data-loss if you are writing at
>> CL.ANY where a hint counts as a write. If you are writing at CL.ONE or above
>> then at least one replica must receive the data for the write to succeed, so
>> losing hints will not cause data-loss.
>>
>> If a hint is not delivered then the replica to which it was intended will
>> become consistent after a read-repair, or after manual anti-entropy repair.
>>
>> Sam
>>
>> --
>> Sam Overton
>> Acunu | http://www.acunu.com | @acunu
>>
>
> If you run nodetool tpstats on each node in your cluster and ensure none of
> them have an active or pending threads in the Hinted stage no hints are
> currently being delivered. But as pointed out above Hinted Handoff is a best
> effort system.
>

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