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From Sven Stark <sven.st...@m-square.com.au>
Subject Re: nodetool repair keeping an empty cluster busy
Date Thu, 12 Dec 2013 02:10:00 GMT
Thanks Rob.

Well, I ran the repair only against the empty keyspace. C* version is
1.2.8. I guess I'll try to recreate it some time next week on two or three
test hosts and if the same behaviour occurs I'll file a bug report.

Cheers,
Sven


On Thu, Dec 12, 2013 at 12:58 PM, Robert Coli <rcoli@eventbrite.com> wrote:

> On Wed, Dec 11, 2013 at 1:35 AM, Sven Stark <sven.stark@m-square.com.au>wrote:
>
>> thanks for replying. Could you please be a bit more specific, though. Eg
>> what exactly is being compacted - there is/was no data at all in the
>> cluster save for a few hundred kB in the system CF (see the nodetool status
>> output). Or - how can those few hundred kB in data generate Gb of network
>> traffic?
>>
>
> The only answer I can come up with is that the Merkle trees generated and
> compared by repair are of a fixed size, and don't scale with the data
> present in the cluster. While I'm pretty sure each node can be aware that
> it has little to no data to repair, it generates and compares the trees
> anyway. It's a bit surprising that this might be Gbs of network traffic...
>
> The system keyspace will always have some data in it, have you tried only
> compacting your empty keyspace instead of the whole node?
>
> If so, and it exhibits the same behavior, that seems like a bug or at
> least unexpected behavior to me. If you're running a modern version of
> Cassandra, I would file a JIRA.
>
> =Rob
>
>

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