Memory based file system (ramdisk) on FreeBSD

To create a ramdisk for /tmp and detach it on FreeBSD 8

# /sbin/mdmfs -M -S -o async -s size md0 /tmp

Don't forget to chmod +w for read/write

# chmod +w /tmp

Detach it and delete from /dev/md0

# /sbin/mdconfig -d -u 0

There is a shell script for the operation

%cat ramdisk.sh
#!/bin/sh

case "$1" in
    create)
            /sbin/mdmfs -M -S -o async -s 18432m md0 /tmp
            /bin/chmod 777 /tmp
            echo "18G ramdisk created on md0 and mounted on /tmp"
            exit 0
            ;;
    destory)
            /sbin/umount /tmp
            /sbin/mdconfig -d -u 0
            echo "ramdisk umounted from /tmp and destory from md0"
            ;;
    *)
            echo "Usage: `basename $0` {create|destory}" >&2
            exit 64
            ;;
esac

Caution! This is for specificed purpose only! You have to modify the parameters if you want to use it.