I actually went the same route, sort of, and bought a QNAP for the speed relegating Drobo to be a backup destination for the QNAP and some other non-critical stores. The main driver for me was the lack of speed. I get around 24MB/sec for Drobo via FW800 whereas on the QNAP it’s around 60MB/sec via a remote mount (AFP).
That move isn’t for everyone in that any NAS is going to require a bit more technical know-how than Drobo or any DAS. It’s all about what you want/need versus what you are willing to invest. To take a stab at your questions:
- heterogeneous disk sizes support
QNAP…none. It’s RAID5 and so if you have two 1TB and two 2TB your usable space will be ~3TB. The rest will be wasted unless you build a second volume or replace the other two drives.
- on-line disk size upgrade for a single RAID
Works if you take the above into consideration. It’s a lengthy process just as it would be in Drobo in that you replace one drive…wait for the rebuild to finish…replace the next and so on. The difference is the number of drives. With QNAP you need to swap all four drives to use all of the space. With Drobo you need to swap two. Adding a larger drive to Drobo in one slot doesn’t get you any additional storage (play with the Drobulator and see).
Quieter. I tend to have more vibration and fan noise from Drobo.
Depends on the model. The QNAP four slot is more expensive than Drobo by about €100. The QNAP 8 slot is less expensive than DroboPro. (Street prices for both.) However for that price difference you are getting a box with more memory and a faster CPU, which I believe is what contributes to the speed differences. Also, every QNAP supports iSCSI out of the box if that’s the sort of thing that you need. And it provides a lot more troubleshooting info (no encrypted logs to deal with) if you know how to use that sort of thing.
The downside is that QNAP isn’t locally attachable via USB or FW such that it looks like one big disk. You must remote mount via SMB, AFP or NFS. That’s not a huge problem since I just add an login item to mount when I log in. Even remote mounted it’s hella fast so I don’t really care whether it’s local or not.
If you’re technically inclined then QNAP is easy to set up. If not then it will be a challenge only because you need to understand the various types of RAID, what volumes are, etc.
In the end I think a fair comparison (speed aside) is to say that a NAS is a lot like Linux, not for the technophobe or non-geek. Linux has come a long way to be more accessible to Joe Average but you still need some technical chops to make it work well. Drobo is more of a set it and forget it device with no option to do otherwise. 
You sacrifice speed and the ability to know what is going on with the box in exchange for not having to learn a lot of techno-jargon.
The summary of all of this is that I still use Drobo but in a non-critical/if it fails “so what” scenario. It’s achilles heel is that it is a complex device that is: a) underpowered by a large margin*; b) tries to mask that complexity requiring queries to DRI support whenever it farts; c) has had manufacturing quality issues (I’m on my third, first was replaced by the reseller due to FW and fan h/w issues, second replaced under warranty when the SATA controlled went tango uniform).
I’ve had drive issues with Drobo as well that looked like a Drobo problem (see no ability to troubleshoot and limited info from DRI support when a case was filed) but may have been a bad run of WD GP 1.5TB drives**. I only figured this out when I moved the WD GP drives to the QNAP and popped some older Hitachi 1TB drives in Drobo. I was able to read SMART info on the WD drives and started to see errors piling up.
My one solid critique of DRI and Drobo are that they seemingly want to be the “Apple” of data storage. That’s a noble goal but the execution is flawed. While my Mac “just works” I can actually drop down to the BSD level and troubleshoot the thing myself if the need arises. I’ve never had to call Apple for anything other than pure hardware problems. DRI’s approach to Drobo is much like iPod or iPhone where you can’t see any of the magic smoke inside. Trouble is that any RAID device (and BeyondRAID is hybrid RAID) is much more complicated than iPod or iPhone. However, unless you buy DroboCare you are pretty much stuck for support after the first year (other than downloading updates when available and perusing this forum). What I mean by that is that if your Drobo does have a hiccup you cannot open a support case to have that encrypted log at least looked at so you know whether it’s a drive or Drobo issue. Yes I know you can de-crypt the logs (not applicable to DroboPro however) but if the box actually did more than provide cheeky status messages you wouldn’t need to do either.
A more minor critique is that the Drobo itself is built a bit on the cheap. The components are generally lower end (smartphone CPU…small amount of DRAM, sometimes noisy fans, and I lost a drive door on my second Drobo because of the tightness between drives) though the price tends to be on par with more solidly built boxes. If I were CEO for a day I’d drop at least a 1.0Ghz CPU in the thing, 1.5Ghz if possible and switch to metal drive trays and better isolation between drive cage and cabinet to reduce vibration.
So…if someone were to ask me whether I recommend QNAP over Drobo the answer is “it depends”. If you’re capably technical or require high performance and are willing to live with the few tradeoffs that RAID5 or RAID6 entails (namely drives of different sizes) then go for it. If not or you just want to make use of that pile of assorted SATA drives you have laying about and can live with the performance issues then get a Drobo.
In both cases I highly, strongly recommend backing up since RAID doesn’t protect you against accidentally deleting something AND both RAID and BeyondRAID can and have failed in the past.
- As to performance I’m speaking only of Drobo and Drobo second gen. I know not whether Drobo S/FS/Pro is faster and by what margin. DRI doesn’t publish the CPU and DRAM values for their boxes and I haven’t seen any recent messages or documents from Mark giving marketing’s view on performance.
** These were the latest and greatest WD GP 1.5TB drives so it wasn’t a firmware issue. Three of the four have had to be returned to WD so far and no I don’t run my QNAP or Drobo 24 by 7.[hr]
@rrevin…they’re not better, just different. No one from DRI is going to say anything on this thread. Your mistake is confusing Drobo for a NAS, which it ain’t. If you need high-performance, even on a good day Drobo won’t rock your world.
As to your specific issues, that’s something I’d work with support on. Do know that QNAP won’t be a panacea for all that ills you either. They have had their own batch of performance issues (peruse their forum). From 2.7.x until the latest firmware (so for much of this year) they had problems where they’d go offline for no reason when accessing them via wireless (WLAN -> GigE switch -> QNAP) and throughput was down around USB speed for a GigE connected box. This is fixed in their latest firmware but my point is that BOTH boxes are complex devices and neither will be 100% flawless. There are several gripes about iSCSI performance still (and QNAP don’t ship with an initiator and the freeware one they recommend is reported to be crash prone by some).
