Thunderbolt NAS vs software RAID

Those of you who have been following along on my mass storage adventures for the last month or so know that all of the OWC Thunderbolt-attached SSDs I’ve tried — two 4M2’s and one Mercury Pro U.2 — have been unreliable when connected to my Windows PCs. Repeated calls to OWC have not resulted in any solutions, and I get the impression that the devices were developed and tested on Macintosh computers, and that Windows attachments were an afterthought, and not nearly as bulletproof. I don’t really know about the OWC Thunderbolt reliability with Macintosh computers, but I think it’s a lot better than I’ve been experiencing with PCs, because, if it’s not, OWC wouldn’t be selling many of these boxes.

But for this post, I’m going to set aside the OWC reliability issues, and contrast two boxes, the OWC Accelsior 8M2 and the QNAP TVX-h874T.

• The OWC box performs no RAID functions. It is meant to be used with OWC’s SoftRAID program. The QNAP NAS performs the function of creating, updating, and managing arrays.
• Both offer Thunderbolt connections for local computers. The OWC NAS also offers 2.5 GbE as standard, and 10 GbE and 25 GbE with an optional card.
• Both hold 8 SSDs. The QNAP box accepts 8 SATA SSDs and two M.2 drives, and the OWC one 8 M.2 ones. The raw speed of the two are different, but the system level speeds I observed are about the same.
• Configured with 8 4 TB SSDs, the cost of the two approaches is about the same, with the NAS coming in a little higher.
• Both claim to offer transparent access to several computers. In the case of the OWC device, attachment to only one computer at a time is possible. The QNAP NAS can attach to many computers simultaneously.
• Attachment to multiple computers works great for the NAS. Attachment to multiple computers hasn’t worked at all for me with the OWC box.
• SoftRAID on Windows offers RAID 0, 1, 10, 5 and JBOD. The QNAP NAS offers RAID 0, 1, 10, 5, 6, 50, and 60 and JBOD.
• SoftRAID uses CPU cycles on the host computer to form the RAID. The QNAP NAS does not.
• SoftRAID uses more Thunderbolt bandwidth than the NAS for write operations on RAID 5 and 10. It would use more for RAID 6, 50, and 60 if it offered those functions.
• SoftRAID offers limited visibility into how the RAID is connected and performing. The QNAP NAS offers and extensive suite of management tools.
• The QNAP NAS has an extensive collection of version management tools. SoftRAID is very limited in that regard.
• The QNAP NAS has many applications for specialized file services, such as media provision to hi-fi’s and TV’s, and storage for and access to security camera data.
• Both say that you can construct a new RAID after a hardware failure without losing data. I have tested this with the QNAP boxes, and it is true. I haven’t tested it with the OWC box.
• The NAS offers hardware compression. The OWC solution depends on your OS for that.
• The NAS offers data deduplication. The OWC box does not.
• The NAS offers cloud storage and management features. I have not tested those.
• You can network together QNAP NAS’s to have multiple appearances of the same datasets.
• You can add a M.2 cache to the SATA storage on the NAS. I haven’t tested this, and it’s not clear to me what, if any, performance improvements are possible.
• The NAS is significantly larger.
• Both are quiet, and suitable for an office environment.
• The QNAP NAS prompts you with a front panel message with the Thunderbolt connection is dropped or restored. The OWC box changes the color of the logo on the front panel to indicate whether the Thunderbolt connection is live, but this is not dependable. It can say it’s connected when it’s not. OWC sent me something they called Cling-Ons (clever name, huh?) that they said would fix this but it did not.
• SoftRAID presents the array to the operating system as a local disk. You need to map the NAS to have a local disk appearance, and even then it’s not totally a local disk; for example, ATTO refuses to run against it.

If I hadn’t had the reliability problems with the OWC boxes, I wouldn’t have gone to the QNAP NAS, but now that I’m using the NAS, I think it is a much better solution for me than the OWC box would be even if the OWC box worked reliably in my PC environment.