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From "Matthew O'Riordan" <m...@ably.io>
Subject Re: ALL range query monitors failing frequently
Date Thu, 29 Jun 2017 09:51:17 GMT
Thanks Kurt, I appreciate that feedback.

I’ll investigate the metrics more fully and come back with my finding.

In terms of logs, I did look in the logs of the nodes and found nothing I
am afraid.

On Wed, Jun 28, 2017 at 11:33 PM, kurt greaves <kurt@instaclustr.com> wrote:

> I'd say that no, a range query probably isn't the best for monitoring, but
> it really depends on how important it is that the range you select is
> consistent.
>
> From those traces it does seem that the bulk of the time spent was waiting
> for responses from the replicas, which may indicate a network issue, but
> it's not conclusive evidence.
>
> For SSTables you could check the SSTables per read of the query, but it's
> unnecessary as the traces indicate that's not the issue. Might be worth
> trying to debug potential network issues. Might be worth looking into
> metrics like CoordinatorReadLatency and CoordinatorScanLatency at the table
> level https://cassandra.apache.org/doc/latest/
> operating/metrics.html#table-metrics
> Also if you have any network traffic metrics between nodes would be a good
> place to look.
>
> ​Other than that I'd look in the logs on each node when you run the trace
> and try and identify any errors that could be causing problems.
>



-- 

Regards,

Matthew O'Riordan
CEO who codes
Ably - simply better realtime <https://www.ably.io/>

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