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Date: Thu, 11 Oct 2012 15:46:59 -0500
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 <CAAam9stLqi9-NtS5ipdsRni18kg+imkAiRowKcDRcvZUsdYgzA@mail.gmail.com>
Subject: Re: READ messages dropped
From: Tyler Hobbs <tyler@datastax.com>
To: user@cassandra.apache.org
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On Wed, Oct 10, 2012 at 3:10 PM, Tamar Fraenkel <tamar@tok-media.com> wrote:

>
> What I did noticed while looking at the logs (which are also running
> OpsCenter), is that there is some correlation between the dropped reads and
> flushes of OpsCenter column families to disk and or compactions. What are
> the rollups CFs? why is there so much traffic in them?


The rollups CFs hold the performance metric data that OpsCenter stores
about your cluster.  Typically these aren't actually very high traffic
column families, but that depends on how many column families you have
(more CFs require more metrics to be stored).  If you have a lot of column
families, you have a couple of options for reducing the amount of metric
data that's stored:
http://www.datastax.com/docs/opscenter/trouble_shooting_opsc#limiting-the-metrics-collected-by-opscenter

Assuming you don't have a large number of CFs, your nodes may legitimately
be nearing capacity.

-- 
Tyler Hobbs
DataStax <http://datastax.com/>

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<div class=3D"gmail_quote">On Wed, Oct 10, 2012 at 3:10 PM, Tamar Fraenkel =
<span dir=3D"ltr">&lt;<a href=3D"mailto:tamar@tok-media.com" target=3D"_bla=
nk">tamar@tok-media.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail=
_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:=
1ex">
<br>What I did noticed while looking at the logs (which are also running Op=
sCenter), is that there is some correlation between the dropped reads and f=
lushes of OpsCenter column families to disk and or compactions. What are th=
e rollups CFs? why is there so much traffic in them?</blockquote>
</div><br>The rollups CFs hold the performance metric data that OpsCenter s=
tores about your cluster.=A0 Typically these aren&#39;t actually very high =
traffic column families, but that depends on how many column families you h=
ave (more CFs require more metrics to be stored).=A0 If you have a lot of c=
olumn families, you have a couple of options for reducing the amount of met=
ric data that&#39;s stored: <a href=3D"http://www.datastax.com/docs/opscent=
er/trouble_shooting_opsc#limiting-the-metrics-collected-by-opscenter">http:=
//www.datastax.com/docs/opscenter/trouble_shooting_opsc#limiting-the-metric=
s-collected-by-opscenter</a><br>
<br>Assuming you don&#39;t have a large number of CFs, your nodes may legit=
imately be nearing capacity.<br clear=3D"all"><br>-- <br><font color=3D"#88=
8888">Tyler Hobbs<span></span><br>
<a href=3D"http://datastax.com/" target=3D"_blank">DataStax</a><br></font><=
br>

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