Thinking about adding another one to mine. Whuch did you get and what do you think so far?
If you don't mind putting a little effort into it, and depending on exactly what you need it for, I'd recommend just building your own. You can get more for cheaper and the FreeNas OS is adequate and free! lol. Mine is a 16TB ZFS Raid-z2 setup (similar to raid6 if you aren't familiar with zfs). So it's actually 6 x 4TB drives. When I built it it cost me about 1500 to build, drives and everything. The closest commercial NAS product I could find with similar hardware features was Synology's Diskstation 8 Bay (DS 1815+) With 8 x 3TB drives. Which cost almost 1900 dollars. The 5 bay (DS 1515+) with 5 x 3 TB drives is still a little over 1700 with less overall space for a raid 6 style setup. At the time when I built my NAS (like 2 years ago), I'm pretty sure those 2 Synology systems were higher priced. I can't say for sure but I seem to remember the 8 bay with 8 x 3TB being more like 2200 at the time. At the same time, mine would be cheaper to build now because the price of the drives has come down. I paid 175 per drive and you can get them for 150 now meaning it's at least $150 cheaper now. Or if you want to spend a little more since I build mine WD released the Red Pro drives for even better reliability in a NAS ($210 for 4TB currently). Granted you may not be looking for something that big, but even with smaller systems you can get by cheaper building your own for a quality system. That said if you aren't extremely worried about reliability and redundancy, some of the lower end systems would probably be cheaper than building your own. For example, if I wanted to add another, smaller NAS for some reason and planned to back up it's contents to my current NAS, I could get by with cheaper drives and such. Potentially make the cheaper consumer grade NAS as cost effective as building my own.
Just to note, the reason I was looking at Synology systems with the drives already is they use WD Red drives, which is what I decided to use in my NAS. A lot of cheaper lower end NAS systems use consumer grade drives in their NAS. Some of the cheaper WD and Seagates even use green or seagates equivalent drive.
The Synology OS is probably a little better than FreeNas. But I wouldn't say it's 200 to 400 dollars better. And only reason I say better is it's more user friendly. I think FreeNas has all the same features, or at least has a plugin available to provide the same feature. I also like how you can run FreeBSD jails on FreeNas. Not sure if you can do that on Synology or not. I run a Plex server and a little shell server that I use for tunneling directly on the FreeNas box. Makes it convenient. You can also do things like set up a torrentbox and such on it if you do that sort of stuff. Another big kicker is both of those Synology's I mentioned come with very limited amounts of memory. They come with only 2GB and expand up to 6GB. I have 32 GB in mine atm, and can expand to 64 GB.
If you were to use a ZFS raid-r1 or raid-r2 type system (highly do not recommend raid 5 or raid-z1 style setup for the size drives used today) performance with that little bit of memory would be pretty slow. ZFS raid systems rely on having lots of ram for caching things and such to increase performance. Even with the double parity I get read and write speeds > 400 MBps in most situations. Simultaneous read write is around 200 MBps. And with 4 port link aggregation, that gives me plenty to do multiple HD movie streams off the NAS at the same time. I can copy data from 3 different machines simultaneously and each max out a 1 Gbps port. My limiting factor there is the 4 port LACP though not the write performance of the NAS raid array.
Also I feel the ZFS raid systems is superior to standard Raid5 or Raid6 because it has active error correction in it that Raid 5 and 6 doesn't. If data gets corrupted on one drive in Raid5 / Raid6 that corruption is duplicated to your redundancy, and you can more easily loose your data. ZFS has stuff in place to prevent that and instead auto repairs corrupted data from the redundancy (I'm talking about data corruption from failed HDD sectors and such). ZFS also does a better job at rebuilding and dealing with potential problems during a rebuild. I'm not sure if the Synology OS even supports ZFS, but it's something to keep in mind.
