I am currently building a NAS for about 24 TB of storage. Video files, slow access, long term storage. No performance issues.
I am currently undecided between buying a JBOD case and installing OpenSolaris (because of ZFS), or purchasing a Nexenta license. The difference is about $ 12.500 for licenses over three years.
What would you see as the main advantage in purchasing a nexenta license, beside the support? Did nexenta really enhance the basic OpenSolaris, or is it just a lot of marketing speak? No one really wanted to answer that question.
P.S. With the nexenta license pricing I am even thinking of going with Windows Storage Server.
(Disclosure: I am a Nexenta developer)
For NexentaStor 24 TB License cost would be ~3000 (Silver) or ~5500 (Gold). (+20% per year Upgrades/support from second year). Take a look at http://www.nexenta.com/corp/store
Nexenta (core and stor) are currently based on b134. It has access to multiple Open-source plugins (nexentastor.org), and the WebUI provides access to more underlying ZFS features. It also includes replication/snaphotting services.
Featurewise, Nexenta first added COMSTAR/zfs integration, that later became available in OpenSolaris. It was the first to add safe upgrades (via apt-clone). It also developed the VTape library to virtualize zvols over tape (http://www.nexentastor.org/projects/vtape). It was the first appliance to provide dedup. It follows upstream features quickly, and backports fixes to the stable build.
There's a free version you can install to test it.. but it can only be used till you reach 12TB of used storage (nexentastor.org). You can also install the free NCP iso, and community developed NAS interface (napp-it).
(Disclosure: I build NexentaStor based solutions)
Take a look at http://www.informationweek.com/news/software/open_source/showArticle.jhtml?articleID=227600191&subSection=Hosted+Software - ultimately 1PB on NexentaStor in mission critical - stability is not a problem.
If you're looking for Enterprise quality and support NexentaStor is the way forward - period. With the likes of Bill Moore, Richard Elling, Garrett D'Amore involved directly with Nexenta the future is very secure indeed.
De-dupe rock on NexentaStor - just make sure you give it enough memory! It's cheaper that WSS, EMC, 3PAR et al.
If you're in the UK take a look at http://www.va-technologies.com/sbb for a good place to start.
As for Windows Storage Server, its SIS/dedup is at the file level versus block level for ZFS and also not real-time.
NexentaStor is based on OpenSolaris, so it also carries basically the same baggage (memory hog, stability, etc.).
The one to watch is FreeNAS and its ZFS support when they roll in SIS/dedup!