FreeNAS is awesome.

Does anyone know of a way to configure FreeNAS (or an alternative FS, such LizardFS or Tahoe LAFS) that can provide the feature set of Isilon OneFS (not the performance) with an open source implementation?

That is,

1. to add more storage, just add another machine (everything looks like one big volume, irrespective of machine/disk boundaries).

2. replication / error correction / raid works across the entire fleet of machines; that is, you can configure it so that up to 1-disk per node, and up to 2-nodes overall can die without damage to data

3. snapshots