I am using mount -t tmpfs tmpfs /home/mc/server15/ramworld to make a ramdisk for my world. I copy the map from HDD to ramdisk with rsync -a /home/mc/server15/world/ /home/mc/server15/ramworld then crontab rsync -a /home/mc/server15/ramworld/ /home/mc/server15/world to sync the ramdisk to hard drive. All seems to be working well but I have yet to reboot and find out. I just realized something today that is scaring me a little: when i ls /home/mc/server15 the world folder is green like the ramdisk folder, does that mean it has somehow became a ramdisk and I could lose the map upon reboot? I have been doing hourly tarballs just in case.
I do hourly backups against my ramdisk, as well as copying to a HD location upon shutting down, and copying to the ramdisk location upon starting up. Your biggest worry is if your server up and crashes, or you lose power, but that is why you do constant backups so at worst you only lose a short period of time.
Do a test. I found that cp was better than rsync. They took basically the same amount of time, and rsync had a much higher CPU load. rsync's advantage is saving network transfer at the cost of CPU. In this case, that's not an advantage. But, you'll want to test it yourself.
rsync also saves disk io by checking file mod dates. It only takes about 20 seconds to rsync the ramdisk to the hdd. cp took 20 minutes.
