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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: memory_locking_policy parameter in cassandra.yaml for disabling swap - has this variable been renamed?
Date Thu, 28 Jul 2011 12:50:55 GMT
I don't think there's ever been a "memory_locking_policy" variable.
Cassandra will call mlockall if JNA is present, no further steps
required.

On Thu, Jul 28, 2011 at 5:17 AM, Stephen Henderson
<stephen.henderson@cognitivematch.com> wrote:
> Hi,
>
>
>
> We’ve started having problems with cassandra and memory swapping on linux
> which seems to be a fairly common issue (in our particular case after about
> a week all swap space will have been used up and we have to restart the
> process).
>
>
>
> It sounds like the general consensus is to just disable swap completely, but
> the recently released “Cassandra High Performance Cookbook” from Packt has
> instructions for “Stopping cassandra from using swap without disabling it
> system wide”. We’ve tried following the instructions but it refers to a
> “memory_locking_policy” variable in cassandra.yaml which throws an “unknown
> property” error on startup and I can’t find any reference to it in any of
> the cassandra docs.
>
>
>
> I’ve copied the summarised instructions below, does anyone know if this is
> something that ever worked or is there a different variable to set which
> does the same thing? (we’re using 0.7.4 at present and it looks like the
> book was written for 0.7.0-beta-1.10 so it might have been something which
> was abandoned during beta?)
>
> ---
>
> Disabling Swap Memory system-wide may not always be desirable. For example,
> if the system is not dedicated to running Cassandra, other processes on the
> system may benefit from Swap Memory. This recipe shows how to install the
> Java Native Architecture, which allows Java to lock itself in memory making
> it inevitable.
>
>
>
> 1. Place the jna.jar and platform.jar in the $CASSANDRA_HOME/lib directory:
>
> 2. Enable memory_locking_policy in $CASSANDRA_HOME/conf/cassandra.yaml:
> “memory_locking_policy: required”
>
> 3. Restart your Cassandra instance.
>
> 4. Confirm this configuration has taken effect by checking to see if a large
> portion of memory is Unevictable:
>
> $ grep Unevictable /proc/meminfo
>
> Unevictable:        1024 Kb
>
> ---
>
>
>
>
>
> Thanks,
>
> Stephen
>
>
>
> Stephen Henderson – Lead Developer (Onsite), Cognitive Match
>
> stephen.henderson@cognitivematch.com | http://www.cognitivematch.com
>
> T: +44 (0) 203 205 0004 | F: +44 (0) 207 526 2226
>
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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