I am working on implementing a D2D backup solution for ~150 computers based on Crashplan ProE (no cloud storage). For the storage backend, I picked up an Overland Snapserver DX2 head unit and one expansion, with 12x2TB per cabinet and I'm planning on using RAID6 on a per-cabinet level. While the foundation of the system is as a NAS, the DX2 is a "unified" storage provider, as it also has the ability to act as an iSCSI target.
Most things have been good so far, but I'm fairly stuck if I want to go with accessing backup archives through NAS, or through iSCSI. I've determined that there really isn't any noticeable processing or performance overhead associated with iSCSI. I'm mostly concerned with filesystem reliability in the long run, with iSCSI essentially seeming like a feature that's been tacked on. They also only supported 2TB iSCSI volumes until sometime last year, when support for larger volumes was enabled. I'd probably be working with an 18TB iSCSI disk. I've done what I can for trying to recreate possible "worst case" scenarios of sudden power loss, drive removal/reinsert/rebuild, etc and things have seemed okay. I've also seen some commentary indicating that iSCSI may be more appropriate than SMB for the sort of multithreaded file access most conducive to decent performance from Crashplan.
So- the short version- anyone with experience with very large iSCSI disks on "unified" low to mid-end NAS/SAN boxes have any comments on iSCSI file system reliability in the longer term?
Edit: All traffic is going to a Crashplan ProE server from the desktops. The server is the only system that communicates with the storage units. I could have gone with a DAS, but was looking for flexibility. Sorry for not being clear there.