Why Wrong HDDs May Lead to Data Loss

Years ago, not many people owned their own NAS storage solutions. Gigabit Ethernet at the time was a luxury not many people enjoyed, NAS units were horrendously slow, software was generally crappy and decent NAS units were usually very, very expensive. Over the past couple years however, the market has changed quite substantially. NAS units have come down in price, performance is up, and software has become quite good. This in turn has driven tons of growth in the NAS industry with many, many people now opting to keep their precious videos, photos, music, documents, and other important data on their NAS devices.

The beautiful thing about NAS units is that they’re completely self powered and most of them (2-bay and above) feature the ability to run in some sort of RAID configuration. As most of you know, RAID is a good thing. 2-bay NAS owners can run a RAID 1 array which mirrors the two drives so that if one of them fails, the second one still has a copy of the data to replicate onto a fresh drive. Those with more than 2 bays can run RAID 5 configurations which uses a single drive as a parity drive so that if any drive in the array fails, the parity drive is capable of repairing a fresh drive with the data contained on the lost drive. While this redundancy is good, it has also given a number of users a false sense of security. With this redundancy, many users for example stop keeping backups. This of course could be disastrous in the event that a RAID 5 array fails and a second drive fails in the rebuild process.

Another point of failure is the drives themselves. Many users (myself included) have traditionally opted for cheap consumer drives for NAS units. After all, if they work fine in our desktop systems, what’s the problem with using them in a NAS, right? Wrong! If you’re running any RAID array using standard consumer drives such as a Seagate Barracuda, Western Digital Green, etc, your data is at risk.

I’ve had a number of readers ask me why their RAID arrays in their brand new NAS units keep degrading and almost every time, it’s because they’re using either WD Green hard drives, WD Blue hard drives, or Seagate Barracudas. If this happens to you, it’s not the NAS units that are at fault. Don’t return them or RMA them. It’s probably the drives.

Let me explain…

Here’s a simple scenario that may or may not have happened to you.

1. You’re running a file transfer to your NAS and the power goes out in your house. Oops! Should’ve bought a UPS! You go out and buy a UPS. In the meantime…
2. You turn the NAS back on once power is restored and you initiate a rebuild. No big deal.
3. In the power outage, one of your drives developed a bad sector. That’s pretty normal.
4. You read the file with the bad sector and the drive realizes that it can’t read the sector.
5. In a typical desktop scenario, drives can take up to 20+ seconds to attempt a recovery of the bad sector. In a RAID array, most RAID controllers only allow the drive around 7 seconds. After 7 seconds, the perfectly good consumer drive gets dropped out of the RAID array. You get a message that says the “RAID array has degraded”. Crud.
6. You insert a fresh hard drive and initiate a RAID rebuild. No big deal.
7. Another drive in the RAID array realizes it’s got a bad block. Crud.
8. Game over. Your RAID 5 array is broken. Good luck getting your files back in any sort of timely matter. If at all.

This happens. Above is a screenshot of what happens to a Synology NAS when it does. It’ll sometimes happen randomly. It’ll sometimes happen when it’s been physically abused it in some way (drives pulled out accidentally). It happens with Synology, Thecus, QNAP, and every other brand of NAS I’ve tested. It may not happen in a day or a week, but it does happen and it happens quite often.

So now that I’ve struck fear into your hearts and your souls, you may ask “What do I need to do to protect myself from this situation?”. The answer is you need a hard drive with error recovery controls feature. Had you have purchased a drive that has error recovery controls for your NAS, this is the scenario that would occur instead.

1. You’re running a file transfer to your NAS and the power goes out in your house. Oops! Should’ve bought a UPS! You go out and buy a UPS. In the meantime…
2. You turn the NAS back on once power is restored and you initiate a rebuild. No big deal.
3. In the power outage, one of your drives developed a bad sector. That’s pretty normal.
4. You read the file with the bad sector and the drive realizes that it can’t read the sector.
5. In a typical desktop scenario, drives can take up to 20+ seconds to attempt a recovery of the bad sector. In a RAID array, most RAID controllers only allow the drive around 7 seconds. After 7 seconds, the hard drive with error recovery controls tells the RAID controller that it’s got a bad block. The RAID controller then documents the bad block, rebuilds the bad block from the parity in the rest of the array into a different block, then resumes operation as expected.

How Do I Avoid This Issue?

Well, your options are pretty simple actually. Just populate your NAS units with drives that have error recovery controls! Now prior to a few years ago, this meant you’d have to buy some pretty serious gear. This meant enterprise hard drives designed for datacenters such as Western Digital RE4’s, Seagate Constellation’s, etc. The problem is that these drives are at least twice to three times as expensive as a regular hard drive. Of course, they also include enterprise validation, longer MTBF ratings, longer warranties, self-encryption, accelerometers, and a whole bunch of other stuff you probably don’t need and don’t really care for if all you’re trying to do is store some pictures of your last vacation.

This is where NAS oriented drives come in. Unlike your typical consumer hard drive, NAS drives include error recovery controls, but don’t include all of the extra fluff that enterprise users need. This allows manufacturers to keep pricing on the NAS drives closer to what we’d expect on consumer hard drives, yet the drives themselves won’t be a serious risk to your data.

What are the Best NAS HDDs?

In our experience, the two best NAS HDD options available for those looking for a hard drive for their NAS is the Seagate’s NAS HDD which is sold under the brand Ironwolf and Ironwolf Pro and the Western Digital NAS HDD sold under the brand Red and Red Pro. Both companies offer an entry level product with a 3 year warranty for home users as well as a pro level product for businesses with a 5 year warranty. All drives feature error recovery controls and are certified by the top NAS vendors such as Synology, Thecus, QNAP, Netgear, Buffalo, Drobo, and more for the best compatibility.

Seagate Ironwolf / Ironwolf Pro

Specifications

The Seagate Ironwolf and Ironwolf Pro series drives are excellent NAS HDDs that perform well and are reasonably priced. We’ve been running an array of eight Seagate IronWolf 8TB HDDs in our labs here at Gear Primer for several years and have yet to run into any issues. The higher 7,200 RPM spindle speed of the higher capacity Seagate Ironwolf drives can make things a bit faster than the 5,400 RPM Western Digital Reds for those with higher end NAS units with 10GbE however, we’ve experienced little performance difference when working with a standard Gigabit Ethernet setup.

Those running larger arrays and want a more robust drive with a higher warranty and improved durability when used in multiple drive arrays should opt for the Ironwolf Pro series drives as they feature vibration sensors which could reduce the likelyhood of nearby vibrating drives causing read/write issues.

Western Digital Red / Red Pro

Specifications

The Western Digital Red and Red Pro are also fantastic NAS HDD drives that offer a lot of value for the money. In our experience, they’ve exhibited zero issues and are highly recommended. Those planning to run larger drive arrays will be happy to note that the entire lineup of WD Red drives feature vibration sensors, which is nice if you’re planning to build a very large array, but don’t want to opt for costlier pro level drives.

For those with higher performance NAS units running a NAS for businesses, content creation, and other server type users should opt for the WD Red Pro as its faster spindle speed will help in terms of performance.