One of the things which is near and dear to our hearts is NAS storage. That’s because we use a LOT of it! We’ve got nearly 100TB of storage here, and we’re about to add some more because we generate so many videos and we need space to house it.
But Geek Beat is small time compared to BackBlaze, the online backup provider who currently has around 28,000 drives deployed. And over the last couple of months they’ve published some fantastic data about what they are seeing in terms of reliability. I’ve cross referenced their findings with those from an old Google document, and an equally old Carnegie Mellon document, and I’m going to tell you everything you really need to know.
Different Drives for Different Environments
First of all, we’re specifically talking about drives that are being used in storage devices. Not the ones in your computer. They are very different environments, mainly because the storage devices are powered on all the time and see a lot more frequent usage.
You might think, since they’re on all the time, let’s get the energy efficient drives! But going Green with your NAS disks is a bad idea. BackBlaze completely abandoned Green drives because their power up/power down sequences were wearing them out very fast. And let’s face it, you don’t want drives with important information wearing out.
So, then paranoia might lend you to want to purchase enterprise grade drives. After all, they cost more and have a longer warranty so why take chances, right? Well, as it turns out, enterprise drives were failing at a rate of 4.6% annually as opposed to consumer drives which only fail 4.2% of the time. So save your money!
How Long a Life Can You Expect?
The next question that comes to mind is, Ok, when do the drives fail? And now things get really interesting. According to BackBlaze, 22% of their drives fail within 4 years. Now think about that for a minute. Where is all of your data sitting right now? If it’s on an old hard drive, and that’s your only copy, you probably have about a 1 in 4 chance of it dying this year!
Heck, even if you have an old NAS with dual drives, configured in a mirrored array, there is still an unacceptably high chance of losing all of your data after 3-4 years.
Failure Rates Between Brands
Before we get into the recommendations, let’s talk about brands. Because I was shocked to see that there was a huge amount of variability. By far, the Seagate drives are failing at higher rates than Western Digital or Hitachi. On first glance it’s enough to make you want to shy away from the brand altogether.
But should you really do that?
Ok, there are so many different models, sizes, brands, and even ages of drives that I wanted to narrow down the results to see if we could stick to comparing models as closely as possible. So I chose the 3TB drives BackBlaze has deployed.
They’ve got roughly 5,600 Hitachi drives with an average age of around 1.9 years old, another 4,500 Seagate drives with an average age of around 1.5 years old, and 350 Western Digital Reds which average just half a year old.
Now the annual failure rate of the Western Digitals come in at just over 3%, while the Hitachis are just under 1%. Meanwhile, the Seagates have a staggering 10% annual failure rate!
That Seagate number is just too big to ignore. I couldn’t, in good conscious, recommend using a Seagate in any NAS device, because even with redundancy the odds of data loss are just too high. But in comparing the Hitachi and the Western Digital Red, the question is… does the price difference justify the additional 2% annual failure rate?
Well, it depends!
Let’s say you’ve got a 2 drive NAS unit like my QNAP HS-210, and you are going to run it in a striped RAID array, meaning that there is no redundancy, you’re going for all the space you can get just bundled into one giant partition. I would ONLY recommend the Hitachi drives, regardless of price. Because if either fails, you lose ALL the data on both.
But in the same NAS if you were going to run them in a mirrored RAID, where both drives backup one another in case one fails, then the odds of losing them both at the same time is pretty slim for the first 3-4 years. If there isn’t much cost difference, go with the Hitachi. But for a big savings the WDs will do in a pinch.
Personally, I don’t like the odds of just going with a 2 drive NAS, so my strong recommendation is to get at least a 4 bay unit. This will allow you to run a more redundant version of RAID, spreading your data out across more drives and lowering the risk of any single drive failing. Here in our studio we tend to use 8 drive storage arrays, which also provide for dual disk redundancy. Meaning we could lose two drives simultaneously and still use the data in those machines.
Of course, no matter what you do in any given single NAS you will always have some small chance that either the NAS itself will fail, or multiple drive failures will get you, or it could be stolen or damaged by a disaster. So the only way to really sleep at night is to maintain another backup NAS offsite, and schedule frequent replication of the data. Certain devices, such as those from QNAP and Synology have Real-Time Remote Replication built in, and can duplicate themselves to another unit across the Internet, or even to an Amazon cloud instance.
Hope that helps answer a few questions for you! But if you have more, you can tweet ’em @johnpoz and if I can’t answer them I’ll get an expert to do it for us!
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