2011/2/16 Aaron Morton <aaron@thelastpickle.com>
JVM heap memory is controlled by the settings in conf/Cassandra-env.sh

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


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 cassandra-env.sh:

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



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?