Unsurprisingly, there is some question about the methods employed by Backblaze in their analysis. Here's a link to a rebuttal, and as Howard says, YMMV:
http://www.enterprisestorageforum.com/storage-hardware/selecting-a-disk-drive-how-not-to-do-research-1.html On Wed, Jan 22, 2014 at 10:06 AM, Jack Coats <[email protected]> wrote: > I found this post very interesting on current drive lifetimes in constant > use. ... Jack > > ---------- Forwarded message ---------- > From: Backblaze Blog <[email protected]> > Date: Wed, Jan 22, 2014 at 3:34 AM > Subject: What Hard Drive Should I Buy? - Backblaze Blog > > > > What Hard Drive Should I Buy? - Backblaze Blog<http://blog.backblaze.com> > [image: > Link to Backblaze Blog] <http://blog.backblaze.com> > ------------------------------ > > What Hard Drive Should I > Buy?<http://feedproxy.google.com/~r/backblaze/~3/H5gCLWTW04o/?utm_source=feedburner&utm_medium=email> > > Posted: 21 Jan 2014 05:54 AM PST > > [image: > blog-which-drive-to-buy]<http://blog.backblaze.com/wp-content/uploads/2014/01/blog-which-drive-to-buy.jpg> > > My last two blog posts were about expected drive > lifetimes<http://blog.backblaze.com/2013/11/12/how-long-do-disk-drives-last/>and > drive > reliability<http://blog.backblaze.com/2013/12/04/enterprise-drive-reliability/>. > These posts were an outgrowth of the careful work that we've done at > Backblaze <http://www.Backblaze.com> to find the most cost-effective disk > drives. Running a truly unlimited online > backup<http://blog.backblaze.com/2011/02/03/backblaze-is-committed-to-unlimited-backup/>service > for only $5 per month means our cloud storage needs to be very > efficient and we need to quickly figure out which drives work. > > Because Backblaze has a history of openness, many readers expected more > details in my previous posts. They asked what drive models work best and > which last the longest. Given our experience with over 25,000 drives, they > asked which ones are good enough that we would buy them again. In this > post, I'll answer those questions. > > *Drive Population* > > At the end of 2013, we had 27,134 consumer-grade drives spinning in Backblaze > Storage > Pods<http://blog.backblaze.com/2013/02/20/180tb-of-good-vibrations-storage-pod-3-0/>. > The breakdown by brand looks like this: > Hard Drives by Manufacturer Used by Backblaze > Brand Number > of Drives Terabytes Average > Age in Years Seagate 12,765 39,576 1.4 Hitachi 12,956 36,078 2.0 Western > Digital 2,838 2,581 2.5 Toshiba 58 174 0.7 Samsung 18 18 3.7 > > 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<http://blog.backblaze.com/2013/10/28/alas-poor-stephen-is-dead/>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. > > *Excluded Drives* > > 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<http://blog.backblaze.com/2013/02/20/180tb-of-good-vibrations-storage-pod-3-0/>, > 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. > > *Failure Rates* > > 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. > > [image: > blog-fail-drives-manufacture]<http://blog.backblaze.com/wp-content/uploads/2014/01/blog-fail-drives-manufacture.jpg> > > This chart has some more details that don't show up in the pretty chart, > including the number of drives of each model that we have, and how old the > drives are: > Number of Hard Drives by Model at Backblaze > Model Size Number > of Drives Average > Age in > Years Annual > Failure > Rate Seagate Desktop HDD.15 > (ST4000DM000) 4.0TB 5199 0.3 3.8% Hitachi GST Deskstar 7K2000 > (HDS722020ALA330) 2.0TB 4716 2.9 1.1% Hitachi GST Deskstar 5K3000 > (HDS5C3030ALA630) 3.0TB 4592 1.7 0.9% Seagate Barracuda > (ST3000DM001) 3.0TB 4252 1.4 9.8% Hitachi Deskstar 5K4000 > (HDS5C4040ALE630) 4.0TB 2587 0.8 1.5% Seagate Barracuda LP > (ST31500541AS) 1.5TB 1929 3.8 9.9% Hitachi Deskstar 7K3000 > (HDS723030ALA640) 3.0TB 1027 2.1 0.9% Seagate Barracuda 7200 > (ST31500341AS) 1.5TB 539 3.8 25.4% Western Digital Green > (WD10EADS) 1.0TB 474 4.4 3.6% Western Digital Red > (WD30EFRX) 3.0TB 346 0.5 3.2% Seagate Barracuda XT > (ST33000651AS) 3.0TB 293 2.0 7.3% Seagate Barracuda LP > (ST32000542AS) 2.0TB 288 2.0 7.2% Seagate Barracuda XT > (ST4000DX000) 4.0TB 179 0.7 n/a Western Digital Green > (WD10EACS) 1.0TB 84 5.0 n/a Seagate Barracuda Green > (ST1500DL003) 1.5TB 51 0.8 120.0% > > The following sections focus on different aspects of these results. > > *1.5TB Seagate Drives* > > The Backblaze team has been happy with Seagate Barracuda LP 1.5TB drives. > We've been running them for a long time - their average age is pushing 4 > years. Their overall failure rate isn't great, but it's not terrible either. > > The non-LP 7200 RPM drives have been consistently unreliable. Their > failure rate is high, especially as they're getting older. > 1.5 TB Seagate Drives Used by Backblaze > Model Size Number > of Drives Average > Age in > Years Annual > Failure > Rate Seagate Barracuda LP > (ST31500541AS) 1.5TB 1929 3.8 9.9% Seagate Barracuda 7200 > (ST31500341AS) 1.5TB 539 3.8 25.4% Seagate Barracuda Green > (ST1500DL003) 1.5TB 51 0.8 120.0% > > The Seagate Barracuda Green 1.5TB drive, though, has not been doing well. > We got them from Seagate as warranty replacements for the older drives, and > these new drives are dropping like flies. Their average age shows 0.8 > years, but since these are warranty replacements, we believe that they are > refurbished drives that were returned by other customers and erased, so > they already had some usage when we got them. > > *Bigger Seagate Drives* > > The bigger Seagate drives have continued the tradition of the 1.5Tb > drives: they're solid workhorses, but there is a constant attrition as they > wear out. > 2.0 to 4.0 TB Seagate Drives Used by Backblaze > Model Size Number > of Drives Average > Age in > Years Annual > Failure > Rate Seagate Desktop HDD.15 > (ST4000DM000) 4.0TB 5199 0.3 3.8% Seagate Barracuda > (ST3000DM001) 3.0TB 4252 1.4 9.8% Seagate Barracuda XT > (ST33000651AS) 3.0TB 293 2.0 7.3% Seagate Barracuda LP > (ST32000542AS) 2.0TB 288 2.0 7.2% Seagate Barracuda XT > (ST4000DX000) 4.0TB 179 0.7 n/a > > The good pricing on Seagate drives along with the consistent, but not > great, performance is why we have a lot of them. > > *Hitachi Drives* > > If the price were right, we would be buying nothing but Hitachi drives. > They have been rock solid, and have had a remarkably low failure rate. > Hitachi Drives Used by Backblaze > Model Size Number > of Drives Average > Age in > Years Annual > Failure > Rate Hitachi GST Deskstar 7K2000 > (HDS722020ALA330) 2.0TB 4716 2.9 1.1% Hitachi GST Deskstar 5K3000 > (HDS5C3030ALA630) 3.0TB 4592 1.7 0.9% Hitachi Deskstar 5K4000 > (HDS5C4040ALE630) 4.0TB 2587 0.8 1.5% Hitachi Deskstar 7K3000 > (HDS723030ALA640) 3.0TB 1027 2.1 0.9% > > *Western Digital Drives* > > Back at the beginning of Backblaze, we bought Western Digital 1.0TB > drives, and that was a really good choice. Even after over 4 years of use, > the ones we still have are going strong. > > We wish we had more of the Western Digital Red 3TB drives (WD30EFRX). > They've also been really good, but they came after we already had a bunch > of the Seagate 3TB drives, and when they came out their price was higher. > Western Digital Drives Used by Backblaze > Model Size Number > of Drives Average > Age in > Years Annual > Failure > Rate Western Digital Green > (WD10EADS) 1.0TB 474 4.4 3.6% Western Digital Red > (WD30EFRX) 3.0TB 346 0.5 3.2% Western Digital Green > (WD10EACS) 1.0TB 84 5.0 n/a > > *What About Drives That Don't Fail Completely?* > > Another issue when running a big data center is how much personal > attention each drive needs. When a drive has a problem, but doesn't fail > completely, it still creates work. Sometimes automated recovery can fix > this, but sometimes a RAID array needs that personal touch to get it > running again. > > Each storage pod runs a number of RAID arrays. Each array stores data > reliably by spreading data across many drives. If one drive fails, the data > can still be obtained from the others. Sometimes, a drive may "pop out" of > a RAID array but still seem good, so after checking that its data is intact > and it's working, it gets put back in the RAID to continue operation. Other > times a drive may stop responding completely and look like it's gone, but > it can be reset and continue running. > > Measuring the time spent in a "trouble" state like this is a measure of > how much work a drive creates. Once again, Hitachi wins. Hitachi drives get > "four nines" of untroubled operation time, while the other brands just get > "two nines". > Untroubled Operation of Drives by Manufacturer used at Backblaze > Brand Active Trouble Number of Drives Seagate 99.72 0.28% 12459 Western > Digital 99.83 0.17% 933 Hitachi 99.99 0.01% 12956 > > *Drive Lifetime by Brand* > > The chart below shows the cumulative survival rate for each brand. Month > by month, how many of the drives are still alive? > > [image: > blog-36-month-drive-survival-rate]<http://blog.backblaze.com/wp-content/uploads/2014/01/blog-survival-drives-by-month.jpg> > > Hitachi does really well. There is an initial die-off of Western Digital > drives, and then they are nice and stable. The Seagate drives start strong, > but die off at a consistently higher rate, with a burst of deaths near the > 20-month mark. > > Having said that, you'll notice that even after 3 years, by far most of > the drives are still operating. > > *What Drives Is Backblaze Buying Now?* > > We are focusing on 4TB drives for new pods. For these, our current > favorite is the Seagate Desktop HDD.15 (ST4000DM000). We'll have to keep an > eye on them, though. Historically, Seagate drives have performed well at > first, and then had higher failure rates later. > > Our other favorite is the Western Digital 3TB Red (WD30EFRX). > > We still have to buy smaller drives as replacements for older pods where > drives fail. The drives we absolutely won't buy are Western Digital 3TB > Green drives and Seagate 2TB LP drives. > > 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? > > At Backblaze, we will continue to monitor and share the performance of a > wide variety of disk drive models. > > -- > -- > You received this message because you are subscribed to the Google Groups > "NLUG" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/nlug-talk?hl=en > > --- > You received this message because you are subscribed to the Google Groups > "NLUG" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > -- -- You received this message because you are subscribed to the Google Groups "NLUG" group. 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