I just set up a file server running Maverick, and created a mirrored zpool of 2 2TB drives. In my prior experience with ZFS, it will use all available memory to cache from the drives... but now I'm seeing memory usage around 400MB on the server. This tells me that the ZFS ARC cache isn't working. Is this not supported in zfs-fuse? If not, would there be a way to create, say, a 2GB ram disk and use it for ZFS cache?
You've not mentioned how much RAM total you have, and what sort of workload you're putting the array under, but ZFS usually is pretty good at figuring out how big the ARC should be, based on both available memory, IO load and a bunch of other things. It doesn't necessarily mean that taking all available memory is the right thing for ZFS to do.