Backbase, a provider from a cloud-service, posted some research on reliability of HDDs from the consumer market. It seems that HDDs from Hitachi are the most reliable, while Seagate has the worst realiability. Given their experience with over 25,000 drives the results should be labeled as reliable as well.
At the end of 2013, we had 27,134 consumer-grade drives spinning in Backblaze Storage Pods. The breakdown by brand looks like this:
Hard Drives by Manufacturer Used by Backblaze
Number of Drives
Average Age in Years
As you can see, they are mostly Seagate and Hitachi drives, with a good number of Western Digital thrown in. We don’t have enough Toshiba or Samsung drives for good statistical results.
Why do we have the drives we have? Basically, we buy the least expensive drives that will work. When a new drive comes on the market that looks like it would work, and the price is good, we test a pod full and see how they perform. The new drives go through initial setup tests, a stress test, and then a couple weeks in production. (A couple of weeks is enough to fill the pod with data.) If things still look good, that drive goes on the buy list. When the price is right, we buy it.
We are willing to spend a little bit more on drives that are reliable, because it costs money to replace a drive. We are not willing to spend a lot more, though.
Some drives just don’t work in the Backblaze environment. We have not included them in this study. It wouldn’t be fair to call a drive “bad” if it’s just not suited for the environment it’s put into.
We have some of these drives running in storage pods, but are in the process of replacing them because they aren’t reliable enough. When one drive goes bad, it takes a lot of work to get the RAID back on-line if the whole RAID is made up of unreliable drives. It’s just not worth the trouble.
The drives that just don’t work in our environment are Western Digital Green 3TB drives and Seagate LP (low power) 2TB drives. Both of these drives start accumulating errors as soon as they are put into production. We think this is related to vibration. The drives do somewhat better in the new low-vibration Backblaze Storage Pod, but still not well enough.
These drives are designed to be energy-efficient, and spin down aggressively when not in use. In the Backblaze environment, they spin down frequently, and then spin right back up. We think that this causes a lot of wear on the drive.
We measure drive reliability by looking at the annual failure rate, which is the average number of failures you can expect running one drive for a year. A failure is when we have to replace a drive in a pod.
A year and a half ago, Western Digital acquired the Hitachi disk drive business. Will Hitachi drives continue their excellent performance? Will Western Digital bring some of the Hitachi reliability into their consumer-grade drives?