The NAS setup I 'built' was ... buy a drobo, shove some drives in it, done. The drobo I use isn't really a NAS, but the Drobo FS is. Either way, it's not exactly going to fit your requirements...
Drobo/Drobo S:
- Pricey
- It's basically a DAS, so you can't manage it without having it connected to an intermediary.
Drobo FS:
- Even Pricier
- You can mount it as a network share in Windows and use the Dashboard to apply all kinds of login credentials to it, but it's pretty basic share-level credentials.
- If your switch can't handle jumbo frames around 7.5k-8k large, forget it, performance will be bunk.
- Short of an earthquake, fire, major electrical surge, or whatnot, you won't lose data. You can set dual-redundancy on the drives so you can have two of the five fail simultaneously and lose nothing.
One thing you didn't list but that may or may not be a big consideration is that with any drobo you never have to touch the configuration (managing hot spares and partition sizes and whatnot) and you can upsize the array just by pulling one drive out and replacing it with a larger one, on the fly. No intrusion. So you can put in whatever you have on hand - say a 750g, 750g, 1tb and 2 empty bays and get some space. Then later fill the empty bays and your storage just increases silently and automatically. Then later on grab a larger drive to replace your smallest one, and you magically just get the space appended without any interaction.
One thing I can definitely recommend - if it's just dead storage and not running a series of live VM instances, the drives you want are the WD Green series or the Seagate Barracuda LP series. They go up to 3TB in some instances, are dirt-cheap, and plenty fast enough for this.
I'd probably look into some of the standalone NAS systems that are listed on newegg, google for reviews, all that stuff you've probably already done
