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From Donald Smith <Donald.Sm...@audiencescience.com>
Subject RE: Dangers of "sudo swapoff --all"
Date Thu, 13 Feb 2014 23:10:57 GMT
I meant to say "Doing "sudo swapon -a" on that node fixed the problem.

From: Donald Smith [mailto:Donald.Smith@audiencescience.com]
Sent: Thursday, February 13, 2014 2:57 PM
To: 'user@cassandra.apache.org'
Subject: Dangers of "sudo swapoff --all"

I followed the recommendations at http://www.datastax.com/documentation/cassandra/2.0/webhelp/index.html#cassandra/install/installRecommendSettings.html
and did:

$ sudo swapoff -all

on each of the cassandra servers in my test cluster.

I noticed, though, that sometimes the cassandra server and other processes on one of the nodes
suddenly crashed, with no messages indicating why.

It turns out that on that node there wasn't much memory, and I was running other processes,
so when the OS detected that there was insufficient memory for an operation, it unceremoniously
killed some processes.  Doing "sudo swapo -a" fixed the problem.  This happened on both CentOs
6.2 and CentOS 6.4.

So, if you do "sudo swapoff -all" make sure you're not going to run out of memory!

Donald A. Smith | Senior Software Engineer
P: 425.201.3900 x 3866
C: (206) 819-5965
F: (646) 443-2333
donalds@AudienceScience.com<mailto:donalds@AudienceScience.com>

[AudienceScience]


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