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From: Yan Chunlu <springrider@gmail.com>
Date: Wed, 13 Jun 2012 19:39:48 +0800
Message-ID: 
 <CAOA66tFS0SMysudt___4f6pwPZghSQtWv8dc6r0n4HBkSSz3HQ@mail.gmail.com>
Subject: how to reduce latency?
To: cassandra-user@incubator.apache.org
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I have three nodes running cassandra 0.7.4 about two years, as showed below:
10.x.x.x      Up     Normal  138.07 GB       33.33%  0

10.x.x.x     Up     Normal  143.97 GB       33.33%
 56713727820156410577229101238628035242
10.x.x.x      Up     Normal  137.33 GB       33.33%
 113427455640312821154458202477256070484

the commitlog and data directory are separated on different disk(Western
Digital WD RE3 WD1002FBYS 1TB).


as the data size grow the reads and write time are keep increasing, slow
down the website frequently.

Based on the experience that every time using nodetool to maintain the
nodes, could cost a very long time, consume a lot system resource(always
ended nowhere),  and cause my web service very unstable, I really have no
idea what to do, upgrade seems not solving this either, I have a newer
cluster with have the same configuration but version is 1.0.2, also got
increasing latency, and the new system also suffering unstable problem...

just wondering does that means I must add more nodes(which is also a
painful and slow path)?


[image: Inline image 1]

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<div>I have three nodes running cassandra 0.7.4 about two years, as showed =
below:</div><div><div>10.x.x.x =A0 =A0 =A0Up =A0 =A0 Normal =A0138.07 GB =
=A0 =A0 =A0 33.33% =A00 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=
 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=A0</div><div>10.x.x.x=A0 =A0 =A0Up =A0 =A0=
 Normal =A0143.97 GB =A0 =A0 =A0 33.33% =A056713727820156410577229101238628=
035242 =A0 =A0 =A0</div>

<div>10.x.x.x=A0 =A0 =A0 Up =A0 =A0 Normal =A0137.33 GB =A0 =A0 =A0 33.33% =
=A0113427455640312821154458202477256070484=A0</div></div><div><br></div><di=
v>the commitlog and data directory are separated on different disk(<span st=
yle=3D"background-color:rgb(255,255,255);color:rgb(51,51,51);font-family:Ve=
rdana,Arial,Helvetica,sans-serif;font-size:11px;text-align:left">Western Di=
gital WD RE3 WD1002FBYS 1TB</span>).</div>

<div><br></div><div><br></div><div>as the data size grow the reads and writ=
e time are keep increasing, slow down the website frequently.=A0</div><div>=
<br></div><div>Based on the experience that every time using nodetool to ma=
intain the nodes, could cost a very long time, consume a lot system resourc=
e(always ended nowhere), =A0and cause my web service very unstable, I reall=
y have no idea what to do, upgrade seems not solving this either, I have a =
newer cluster with have the same configuration but version is 1.0.2, also g=
ot increasing latency, and the new system also suffering unstable problem..=
.</div>

<div><br></div><div>just wondering does that means I must add more nodes(wh=
ich is also a painful and slow path)?</div><div><br></div><div><br></div><d=
iv><br></div><img src=3D"http://imgshare.appwill.com/serve.php?file=3D/cs/f=
mz5y24uo8w0k.png" alt=3D"Inline image 1"><br>


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