When running OpenSim on OS X Server – at least in grid mode, the thing you don’t want to happen is for the server to go to sleep or spin down the disks. For some reason this happened on one of my servers where the disk kept spinning down regardless of how the System Settings control panel was configured.
To override the control panel, you can open a terminal session and type the following (with an administrator password):
sudo pmset -a disablesleep 1