I’m playing around with a HP MicroServer running FreeNAS 0.7.2 and had some problems mounting an external USB disk with a EXT3 partition. FreeNAS kept on complaining:
mount: /dev/da1s1 : Operation not supported by device
Very weird. However, trying to check the drive with:
fsck_ext2fs /dev/da1s1
… did the trick. Now the disk is mountable.
After that you can actually manage it from the FreeNas GUI, and have it mount after reboot.
In the volume / disk mgmnt section.