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In-Reply-To: <671D5EC0-4731-4090-9B91-DE6B7E7C75C9@gmail.com>
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Date: Tue, 22 Mar 2011 11:44:33 -0400
Message-ID: <AANLkTin5O23uNxD1Y6nHx5yTjtnwEQCf4i=tEQ=+haib@mail.gmail.com>
Subject: Re: Meaning of TotalReadLatencyMicros and
 TotalWriteLatencyMicrosStatistics
From: Ching-Cheng Chen <cchen@evidentsoftware.com>
To: user@cassandra.apache.org
Cc: Jonathan Colby <jonathan.colby@gmail.com>
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Just as what it named, it's the total microseconds spent on read operations
so far.

Not average.

Regards,

Chen

Senior Developer, EvidentSoftware(Leaders in Monitoring of NoSQL & JAVA )

http://www.evidentsoftware.com

On Tue, Mar 22, 2011 at 11:11 AM, Jonathan Colby
<jonathan.colby@gmail.com>wrote:

> Hi -
>
> On our recently live cassandra cluster of 5 nodes, we've noticed that the
> latency readings, especially Reads have gone up drastically.
>
> TotalReadLatencyMicros          5413483
> TotalWriteLatencyMicros         1811824
>
>
> I understand these are in microseconds, but what meaning do they have for
> the performance of the cluster?   In other words what do these numbers
> actually measure.
>
> In our case, it looks like we have  a read latency of 5.4 seconds, which is
> very troubling if I interpret this correctly.
>
> Are reads really taking an average of 5 seconds to complete??
>
>
>
>

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Just as what it named, it&#39;s the total microseconds spent on read operat=
ions so far.<div><br></div><div>Not average.</div><div><br></div><div>Regar=
ds,</div><div><br></div><div><span class=3D"Apple-style-span" style=3D"bord=
er-collapse: collapse; font-family: arial, sans-serif; font-size: 13px; "><=
p class=3D"MsoNormal" style=3D"margin-top: 0px; margin-right: 0px; margin-b=
ottom: 0px; margin-left: 0px; ">
Chen</p><p class=3D"MsoNormal" style=3D"margin-top: 0px; margin-right: 0px;=
 margin-bottom: 0px; margin-left: 0px; ">Senior Developer, EvidentSoftware(=
Leaders in Monitoring of NoSQL &amp; JAVA )</p><p class=3D"MsoNormal" style=
=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0p=
x; ">
<a href=3D"http://www.evidentsoftware.com/" target=3D"_blank" style=3D"colo=
r: rgb(42, 93, 176); ">http://www.evidentsoftware.com</a></p></span><br><di=
v class=3D"gmail_quote">On Tue, Mar 22, 2011 at 11:11 AM, Jonathan Colby <s=
pan dir=3D"ltr">&lt;<a href=3D"mailto:jonathan.colby@gmail.com">jonathan.co=
lby@gmail.com</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex;">Hi -<br>
<br>
On our recently live cassandra cluster of 5 nodes, we&#39;ve noticed that t=
he latency readings, especially Reads have gone up drastically.<br>
<br>
TotalReadLatencyMicros =A0 =A0 =A0 =A0 =A05413483<br>
TotalWriteLatencyMicros =A0 =A0 =A0 =A0 1811824<br>
<br>
<br>
I understand these are in microseconds, but what meaning do they have for t=
he performance of the cluster? =A0 In other words what do these numbers act=
ually measure.<br>
<br>
In our case, it looks like we have =A0a read latency of 5.4 seconds, which =
is very troubling if I interpret this correctly.<br>
<br>
Are reads really taking an average of 5 seconds to complete??<br>
<br>
<br>
<br>
</blockquote></div><br></div>

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