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From Aaron Morton <>
Subject Re: memory consuption
Date Fri, 18 Feb 2011 00:27:43 GMT
Victor, I'm a bit confused here as we've now got two conversations in this thread. 

Can you please start a new thread about your memory problem, I'm not clear on the details.
Please include...

- cassandra version
- JVM  heap settings from bin/ or conf/cassandra-envsh 
- disk_access_mode
- result from top or ps 
- why what you are seeing is different from what you expect. 


On 18 Feb, 2011,at 01:17 PM, Victor Kabdebon <> wrote:

Already done. The disk access mode is standard in storage-conf.xml (I am using 0.6.6 at the
moment, I will upgrade to 0.7.x later). But this memory consumption is a real issue.

2011/2/17 Aaron Morton <>
Looks like you are using virtual memory for memmapped files. Change the disk_access_mode to
standard if you want to reduce the overall memory usage. 


On 18 Feb, 2011,at 09:34 AM, Victor Kabdebon <> wrote:

Sorry I forgot to say that this is the partial result of : 
ps aux | grep cassandra

Best regards

2011/2/17 Victor Kabdebon <>
Oh right but Cassandra doesn't really respect that, I thought there was another option to
set that.

Just for your information, I set xms and xmx very low with a small amount of data. I am waiting
to be able to connect jconsole, I don't know why it is not reachable at the moment. Here is
my result :

105      26115  0.2 273 1125328 755316 ?      Sl   Feb09  23:58 /usr/bin/java -ea
-Xms64M -Xmx128M

2011/2/17 Aaron Morton <>
set Xms and Xmx in the JVM_OPTS


On 18 Feb, 2011,at 09:10 AM, Victor Kabdebon <> wrote:

Is it possible to change the maximum JVM heap memory use in 0.6.X ?

2011/2/17 Aaron Morton <>
What are you using for disk_access_mode ?
Have you tried reducing the JVM head size?
Have you added the Jna.jar file to lib/ ? This will allow Cassandra to lock the JVM memory.


On 17/02/2011, at 9:20 PM, ruslan usifov <> wrote:

2011/2/16 Aaron Morton <>
JVM heap memory is controlled by the settings in conf/

Memory mapped files will use additional virtual memory, is controlled in conf/Cassandra.yaml

And??? JVM memory heap in cassandra 0.7 is by default half of memory is system in my case
4GB, here is a part of

    case "`uname`" in
            system_memory_in_mb=`free -m | awk '/Mem:/ {print $2}'`
            MAX_HEAP_SIZE=$((system_memory_in_mb / 2))M
            return 0
            system_memory_in_bytes=`sysctl hw.physmem | awk '{print $2}'`
            MAX_HEAP_SIZE=$((system_memory_in_bytes / 1024 / 1024 / 2))M
            return 0
            return 1

I set all this options by default. All my nodes have 8GB of memory. And i affraid that after
some time all my nodes goes to hard swap, and only reboot help them :-(((

PS: as i understand that down sometime of cassandra is normal?

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