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From Mikhail Panchenko...@mihasya.com>
Subject Re: How can OpsCenter show me Read Request Latency where there are no read requests??
Date Wed, 16 Jan 2013 05:55:25 GMT
I haven't used OpsCenter specifically, so this is a guess: often latency
metrics are based on the last N samples and what is graphed are percentiles
(as opposed to a sliding time window). That means that the graph will
remain the same until more requests occur, as the data that the percentiles
are calculated from is not changing (i.e. there are no new samples of
latency being added). If that's not it, then I don't know :D


On Tue, Jan 15, 2013 at 7:28 PM, Brian Tarbox <tarbox@cabotresearch.com>wrote:

> I am making heavy use of DataStax OpsCenter to help tune my system and its
> great.
>
> And yet puzzling.  I see my clients do a burst of Reads causing the
> OpsCenter Read Requests chart to go up and stay up until the clients finish
> doing their reads.  The read request latency chart also goes up....but it
> stays up even after all the reads are done.  At last glance I've had next
> to zero reads for 10 minutes but still have a read request latency thats
> basically unchanged from when there were actual reads.
>
> How am I to interpret this?
>
> Thanks.
>
> Brian Tarbox
>

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