If I had the hardware that you do, I would do it this way:
5x 1TB Disks in the FreeNAS box configured for a single RAIDZ1 pool (I'd actually spring for one more disk and do 6x 1TB RAIDZ2, if I could afford it)
- 1 Datastore for Photos/Videos
- 1 Datastore for Lab
- 1 Datastore for multimedia
1x 1TB Disk in the Zyxel NAS for rsync backup
Here are the assumptions I'm making:
You won't have any heavy usage of the ESXi box (16 GB RAM isn't enough for more than a few guests).
Having some sort of redundancy for ALL the data on your NAS is a Good Idea(TM) and this configuration achieves that.
Redundancy for a backup isn't as important (it's already a copy of what's on the NAS). (Also, you can always add a drive to the Zyxel later.)
It's easier to divide up the storage virtually (datastores) rather than physically (pools). You probably won't notice the performance difference anyways.
Caveats:
Use the WDIDLE3 utility to tell any "Green" drives in the NAS not to park theirs heads so much. Otherwise the greens might die earlier than you want them to (YMMV).
If you do expect to do some heavy disk IO with ESXi, I'd just do local storage rather than NFS because you won't be happy with the performance with this kind of hardware. In that case, I'd do 1x 1TB in the ESXi server and 4x 1TB RAIDZ1 in the NAS. You can even backup your ESXi guests to the NAS with something like Quantm's VM-Pro.
Note that you cannot move from RAIDZ1 to RAIDZ2 (but you can move from a single disk to a mirrored pair), which is why I recommend buying one more disk if at all possible. Any kind of single redundancy (RAIDZ1 or RAID 5) is not as useful as it once was (see my sig for a link to why this is).
This is one of those things where you will potentially get a lot of different answers, all of which make sense depending on the use cases you have in mind. That's why I laid out my assumptions above. In the end, it's up to you to decide what configuration best meets your needs.
