Subscriber Discussion

How To Choose A NAS?

I'm wondering what factors should be taken into account when choosing a NAS device. So far I've been able to list 4 factors that are as follows:

  • Throughtput handling
  • Power consumption
  • Money/TB ratio
  • Maximum storage capacity

Is there any other factor that should be taken into account?

I don't think it can be understated the level of support (warranty terms, length of time, RMA policy) and historical experiance from other users.

There are some NAS appliances sold less HDDs. (Synology comes to mind.) The money/TB ratio may not be a clean metric in this case.

It may not be a fair metric at the first glance, but it is still comparable IF you populate the "HDD-less" NAS appliance with the same hard disks of a "HDD-ful" NAS.

Every NAS I've ever bought has been "sans hard drives". I've seen some that give you the option to come pre-loaded, but they seem to add a substantial mark-up to the drives themselves, sometimes even more than retail.

And I'll second Luis' comment, quality and availability tech support is crucial. I've installed a few QNAP units for a customer that wanted something lower-cost, and while they're USUALLY pretty solid, I have had a very few catastrophic failures... their support guys are knowledgeable enough and have managed to remote in and recover data for me a couple times, but that's only IF I can get ahold of them. Simple lack of ACCESSIBLE support is the main reason I'll never use another QNAP.

Enhance Tech has been pretty good for support - I have an engineer's direct line and email and he's been super helpful and also supported me doing assorted field repairs without voiding warranty.

We're using Promise arrays now, and while support is fairly responsive, holy crap, are their replies ever hard to decipher sometimes, existing somewhere between cryptic and obfuscated. Fortunately, so far I've only needed them to answer basic operational questions, and not to deal any major crises.

But like Luis says, don't underestimate the value of GOOD SUPPORT.

Funny thing I've found with all these different units, it seems the more expensive and "industrial-grade" they are, the less they're able to do what I'd think should be basic functions. I'm not talking about loading on features like media and web servers and whatnot, I mean basic RAID functions... case in point: we needed to upgrade one QNAP unit to larger drives, and QNAP provides a nice little wizard-driven process for this - essentially, swap one drive, let it rebuild... swap another drive, let it rebuild... etc. Time-consuming, but easy-peasy. Enhance arrays, on the other hand, do not support ANY sort of in-place upgrade of drives... and Promise, I don't know as I haven't had to ask yet.

Similarly, the Enhance boxes support thin provisioning of LDs, and I believe (although I haven't had to try it yet) easy expansion of an LD into unused array space... Promise, on the other hand, SAYS it can be done, but states that it would probably take several months to complete a "migration", and their instructions on how to do it were full of errors (few of the steps were where they said they'd be in the menus). Argh!

And to add to all that, it seems to more you pay for these things, the more complex they become to configure anything. QNAP and Synology make it all simple to set up iSCSI targets and LDs in a single process even without needing to use wizards... Enhance makes you go through two or three separate processes to get there... and Promise, I'm not even sure, because it's always taken a lot of clunking around in a half-dozen different places to get it to work properly, and even then, it seems to just suddenly start working without it being clear exactly what part of the process was involved.


Are there any video surveillance specific 'optimizations' that certain NASes might have that others wouldn't?

I know the SAN vendors like to promote such claims but I don't recall hearing such things from NAS vendors.

I feel Matt's pain as I'm sure we've all been there before. I also think he brings up some important feature points: the ability to add disks to a RAID set without destroying the existing array and date, and inserting/upgrading larger drives and somehow making use of that space without destroying existing data.

Gents, thanks for the feedback so far.

@Matt: About QNAP you mentioned "while they're USUALLY pretty solid, I have had a very few catastrophic failures". Out of curiosity, what caused the array to fail?

Regarding Good Support, I agree with you that it is a factor that should be taken into account. I wonder although how we can measure that. Support should be measured regarding response time, number of attemps until problem was finally solved, etc.???

@John: A NAS vendor that comes to my mind and that claims to optimize storage for video surveillance is Veracity with their COLDSTORE device.

Another factor that came to my mind is ONVIF compliance. ONVIF Profile G for video storage is coming out and maybe it is a good factor to be taken into account as well, imho.


QNAP allows you to sequentially upsize the hard drives to increase the storage space? Wow!!! I've never run into a storage product (other than, I believe, COLDSTORE) that allows this. It's a function I've often dreamed about.

Does any other manufacturer do this elegantly?

@Carl: it does indeed, and using standard RAID types as well (the one I did it on was running RAID5). As I say, it was fairly painless, though time-consuming, and the added space isn't available until all drives have been swapped. In fact, it's documented here.

Pretty sure my Synology at home will do it when using SHR ("Synology Hybrid RAID", similar to RAID5 or 6, but with their own twist), although I've never looked to see if it will do it under standard RAID5/6... and I would think something with its own proprietary RAID system, like Drobo, would as well. Edit: in fact, Synology documents the procedure as well.

Beyond that... no idea. I don't suppose it's that complicated a thing: if a system gives you the ability to create an array smaller than the maximum size of available disks, AND the ability to expand that array later, then it should be a simple matter to swap disk, rebuild, swap disk, rebuild, etc. etc. and then once all are swapped, expand the array into the new available space.

@Tiago: in one case, the unit behaved like it had power supply issues; upon sending it in, they said its firmware was corrupted, so they re-flashed it, which fixed it for a while... although it still had intermittent odd problems after that, that still felt like power issues to me. The painful part was that it took weeks of back-and-forth to even get to the point of RMA, usually because responses from them took hours or days... NOT good when one is trying to get help while on-site.

In two or three other cases, it's been a matter of the system burping on one drive in a RAID5 array, then on another before the array was completely rebuilt... granted, on at least one of those, it was running "green" drives as a cost-saving measure (against my specific objections)... since then the customer has also learned to eat the extra cost of using RAID6+spare to avoid such major problems caused by minor glitches.

In at least one of those cases, a QNAP tech was able to remote into the system and get the data back... but again, it was like pulling teeth to get to that point, and only happened after I'd left site.

As far as a metric for "good support" I'd say the main one is response time and accessibility... and this applies to support for ANYTHING!!! If I get a call to a site, find a problem, and need to contact support... I can't be sitting there for hours at $90 per waiting for someone to call me back. A phone number for contact (toll-free, ideally, of course) or fast email contact is crucial, not some web form whose submission goes into the ether with no indication of when you'll hear back.

I'll forgive number of attempts and even ability to solve, in most cases, because I know all too well, sometimes issues don't fully present themselves, or don't make themselves obvious. Some are intermittent, and of course, work fine when you DO get the support guy online. Heck, I'm sure we all regularly have instances where we get a problem call, get onsite, and find everything working fine, only to have it go on the fritz again five minutes after we've left.