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Recently, Backblaze released our 2015 hard drive failure<\/a> rate statistics. After each blog post, and especially popular ones, I spend a large amount of time reading through the comments, answering what I can, and gathering a series of frequently asked questions to help us frame future blog posts better. In order to answer some of these, I spoke with Brian Beach<\/a> (author of our drive stats<\/a> posts), Tim Nufire (author of many Storage Pod<\/a> posts), and Ariel (the man behind our purchasing department). What follows is a list of some frequently asked questions that I hope to update if the data changes, or if we decide to go a bit more in-depth:<\/p>\n We hope to update these if things change, or if there is additional wisdom that we can impart. Hopefully, this helps answer some of the common questions I’ve been seeing while reading the comments surrounding our blogs!<\/p>\n","protected":false},"excerpt":{"rendered":"\n
\nA:<\/strong> At this time we do not have any data about SSD drives. We put a high premium on a good price to density ratio, and currently SSDs are just too expensive at the density that we need. We hope that changes soon and when it does, we\u2019d love to test them!<\/li>\n
\nA:<\/strong> We\u2019re currently well underway with testing of 6TB hard drives<\/a>, but as of yet don\u2019t have enough 8TB drives for a good test in our environment. We do have some, but we hope to get more soon!<\/li>\n
\nA:<\/strong> We use SMART stats to make sure that all of our drives are operating correctly, and you can read more about that on our \u201cHard Drive SMART Stats<\/a>\u201d blog post.<\/li>\n
\nA:<\/strong> Western Digital bought Hitachi in 2012. At that time, Hitachi hard drives rebranded to HGST and is currently run as a separate subsidiary of Western Digital.<\/li>\n
\nA:<\/strong> MTTF is just another way of expressing the annual failure rate (some people call it MTBF). For us, we find the annual failure rate easier to deal with for planning and cost estimation. If the failure rate is 2%, that means we need to plan on replacing 2% of the drives each year.<\/li>\n
\nA:<\/strong> Yes, we prefer to buy low-powered drives as they tend to help us keep our data center costs lower. That said, higher powered drives are not excluded if they perform well in our environment.<\/li>\n
\nA:<\/strong> We\u2019ve done a bit of analysis and in our environment there really is not much of a difference between enterprise and consumer hard drives. You can read our findings on our \u201cEnterprise Drives: Fact or Fiction<\/a>\u201d blog post, but the TL;DR version is that their higher cost does not make up for their performance.<\/li>\n
\nA:<\/strong> When a hard drive fails, we securely wipe the drive and then recycle it.<\/li>\n
\nA:<\/strong> When purchasing hard drives, the most important thing for us to consider is a density to price ratio, but really close to that ratio is the performance of that drive in our ecosystem, depending on which, the density to price ratio can be superseded. If a hard drive is inexpensive and has a lot of density for the price, but fails often, then it is not a viable hard drive for us to purchase in bulk. We often buy small batches of hard drives to test in our Pods, and if they work then we will buy them in bulk.<\/li>\n
\nA:<\/strong> We buy internal hard drives for our Storage Pods and external hard drives for restores. There was a brief period<\/a> when we bought external hard drives for our Storage Pods as they were much less expensive than their internal counterparts, and performed equally well. We have not done this since April of 2013, and are happy to say that the majority of those drives that were \u201cshucked\u201d are still spinning in our data center!<\/li>\n
\nA:<\/strong> While we do use different Storage Pods, the hard drives that we use are spread out throughout most of them. Typically our hard drives don\u2019t experience a high level of vibration, but it is more than one might typically find inside a single hard drive enclosure such as an external hard drive. Of course, some external hard drives are carried around in backpacks, dropped on floors, and such.<\/li>\n
\nA:<\/strong> In our data center, Storage Pods are \u201cup\u201d unless they need to be taken down for maintenance or there is a power outage. This happens infrequently as noted in our SMART Stats post when we talked about \u201cpower cycles.\u201d This begs the age-old question: is it better for your hard drive to turn off your computer when you\u2019re not using it or keep it running? Our vote is to keep them running.<\/li>\n
\nA:<\/strong> The redundancy built into our data storage model with RAID 6, along with our own data integrity checking, and our SMART stats monitoring, ensures that the data we store will be safe and available regardless of the drive models used. This allows us to purchase drives that have a lifecycle cost that is the least expensive when considering the initial cost, warranty, failure rate, product availability, etc. In short, enterprise and consumer drives both deliver the same reliability in our environment, so we choose the drives that have the lowest lifecycle cost.<\/li>\n
\nA:<\/strong> That depends. If you view our data center as a \u201cworst case\u201d scenario for hard drives, then yes, you can surmise that any hard drive<\/a> that a consumer would buy, would perform at a slightly better rate than our hard drives. You could also conclude that the drives that \u201csurvive\u201d in our data center are really good.
\nIf you don\u2019t view it as a stress-test, then no, the data is merely an interesting results summary from a company with a lot of spinning hard drives.<\/li>\n
\nA:<\/strong> Our hard drives are relatively cool, and don\u2019t tend to overheat. We\u2019ve looked at this in-depth and you can read about our findings on our \u201cHard Drive Temperature: Does It Matter?<\/a>\u201d blog post!<\/li>\n
\nA:<\/strong> We love Seagate! This is a common misconception about our hard drive stats posts. Both of our hard drive stat posts indicated a slightly elevated failure rate from their compatriots, however, the price of the Seagate drives cannot be beat, and they work great in our environment. This goes back to the price to density to failure-rate ratio that Backblaze likes to use, and in it, Seagate often comes out on top!<\/li>\n<\/ul>\n