(plus disk)
Ah, so what you mean is your 180TB NAS actually costs nearer £12,000 (based on retail prices of 3.5" 4TB drives).
Still...that's not bad. No data on redundancy method though.
Cloud storage company Backblaze may not quite have the cachet of the folks playing in the Open Compute Project, but that hasn't stopped the company open-sourcing the design it's cooked up for the JBOD-like rigs it uses to power its service. And after receiving a million page impressions for the release of its first design, the …
Given the cost for 3TB drives is hovering around £100, i'd say it's not worth building a 4TB rig - adding 45B of additional storage increases the cost by around £3,500, which just doesn't make sense economically.
Should be able to build the chasis for ~£1,500, so the 180TB version is around £9,000 or 135TB for around £6,000.
The backblaze company are using normal Linux filesystems, is it XFS?, and as research has shown, those filesystems are susceptible to data corruption. There is always a very small risk of data corruption, but if you have very large amounts of data, you will surely get data corruption. And 180TB is bound to have data corruption. The more data, the more problems.
Research about Linux filesystems being unsafe:
http://www.zdnet.com/blog/storage/how-microsoft-puts-your-data-at-risk/169
Large amounts of data always face data corruption, says Amazon engineer:
http://perspectives.mvdirona.com/2012/02/26/ObservationsOnErrorsCorrectionsTrustOfDependentSystems.aspx
Research shows that ZFS is indeed safe, and protects your data:
http://research.cs.wisc.edu/wind/Publications/zfs-corruption-fast10.pdf
".....Research shows that ZFS is indeed safe....." Can it be clustered yet? No? Oh, so when your one ZFS server dies you lose access to all your data. FAIL! This has been pointed out to you countless numbers of times, Kebby, so please stop with the ZFS cheerleader routine until it is enterprise-ready.
You could could build an enterprise supported and clustered NFS 4.1 / SMB3 solution to do this on Windows Server 2012 - use the iSCSI server on each storage array, and then a clustered head end that mounts the volumes in a resilient RAID config. That way you could also use deduplication.