![\"Q1](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/drive-stats-header.jpg\")
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For Q1 2016 we are reporting on 61,590 operational hard drives used to store encrypted customer data in our data center. There are 9.5% more hard drives in this review versus our last review<\/a>, when we evaluated 56,224 drives. In Q1 2016, the hard drives in our data center, past and present, totaled over one billion hours in operation to date. That\u2019s nearly 42 million days or 114,155 years worth of spinning hard drives. Let\u2019s take a look at what these hard drives have been up to.<\/p>\n Below are the hard drive failure<\/a> rates for Q1 2016. These are just for Q1 and are not cumulative, that chart is later.<\/p>\n Some observations on the chart:<\/p>\n We started collecting the data used in these hard drive<\/a> reports on April 10, 2013, just about three years ago. The table below is cumulative as of March 31 for each year since April 10, 2013.<\/p>\n Let\u2019s take a look at what the hard drives we own have been doing for one billion hours. The one billion hours is a sum of all the data drives, past and present, in our data center. For example, it includes the WDC 1TB drives that were recently retired from service after an average of six years in operation. Below is a chart of hours in service to date ordered by drive hours:<\/p>\n The \u201cOthers\u201d line accounts for the drives that are not listed because there are or were fewer than 45 drives in service.<\/p>\n In the table above, the Seagate 4TB drive leads in \u201chours in service,\u201d but which manufacturer has the most hours in service? The chart below sheds some light on this topic: The early HGST drives, especially the 2TB and 3TB drives, have lasted a long time and have provided excellent service over the past several years. This \u201ctime-in-service\u201d currently outweighs the sheer quantity of Seagate 4TB drives we have purchased and placed into service the last year or so.<\/p>\n Another way to look at drive hours is to see which drives, by size, have the most hours. You can see that in the chart below. The 4TB drives have been spinning for over 580 million hours. There are 48,041 4TB drives which means each drive on average had 503 drive days of service, or 1.38 years. The annualized failure rate for all 4TB drives lifetime is 2.12%.<\/p>\n The drives in our data center come from four manufacturers. As noted above, most of them are from HGST and Seagate. With that in mind, here\u2019s the hard drive failure rates by manufacturer. We\u2019ve combined all of the drives, regardless of size, for a given manufacturer. The results are divided into one year periods ending on March 31 of 2014, 2015, and 2016. A couple of times, we\u2019ve noted that we don\u2019t display drive models with fewer than 45 drives. Why would we have less than 45 drives given we need 45 drives to fill a Storage Pod? Here are few of the reasons:<\/p>\n Regardless of the reason, if we have less than 45 drives of the same model, we don\u2019t display them in the drive stats. We do however include their information in any grand total calculations such as drive space available, hours in service, failures, etc.<\/p>\n We often get asked why we don\u2019t buy more WDC and Toshiba<\/a> drives. The short answer is that we\u2019ve tried. These days we need to purchase drives in reasonably large quantities\u20145,000 to 10,000 at a time. We do this to keep the unit cost down and so we can reliably forecast our drive cost into the future. For Toshiba, we have not been able to find their drives in sufficient quantities at a reasonable price. For WDC, we sometimes get offered a good price for the quantities we need, but before the deal gets done something goes sideways and the deal doesn\u2019t happen. This has happened to us multiple times, as recently as last month. We would be happy to buy more drives from Toshiba and WDC, if we could, but until then we\u2019ll continue to buy our drives from Seagate and HGST.<\/p>\n Another question that comes up is why the bulk of the drives we buy are 4TB versus the 5TB, 6TB, 8TB, and 10TB drives now on the market. The primary reason is that the price\/TB for the larger drives is still too high, even when considering storage density<\/a>. Another reason is availability of larger quantities of drives. To fill a Backblaze Vault<\/a> built from 20 Storage Pod<\/a> 6.0 servers, we need 1,200 hard drives. We are filling three or more Backblaze Vaults a month, but the larger size drives are hard to find in quantity. In short, 4TB drives are readily available at the right price, with 6TB and 8TB drives getting close on price, but still limited in the quantities we need.<\/p>\n For Backblaze, there are three reasons a drive is considered to have \u201cfailed\u201d:<\/p>\n Note: Our stand alone Storage Pods use RAID-6, our Backblaze Vaults use our own open-sourced implementation of Reed-Solomon<\/a> erasure coding, instead. Both techniques have a concept of a drive not syncing or staying synced with the other member drives in its group.<\/p>\n We publish the hard drive stats<\/a> data on our website with the Q1 2016 results there as well. Over the years, thousands of people have downloaded the files. One of the folks who downloaded the data was Ross Lazarus, a self-described grumpy computational biologist. He analyzed the data using Kaplan-Meier statistics and plots<\/a>, a technique typically used for survivability analysis. His charts and analysis present a different way to look at the data and we appreciate Mr. Lazarus taking the time to put this together. If you\u2019ve done similar analysis of our data, please let us know in the comments section below\u2014thanks.<\/p>\n","protected":false},"excerpt":{"rendered":" For Q1 2016 we are reporting on 61,590 operational hard drives used to store encrypted customer data in our data center. There are 9.5% more hard drives in this review versus our last review when we evaluated 56,224 drives. In Q1 2016, the hard drives in our data center, past and present, totaled over one billion hours in operation to date. That\u2019s nearly 42 million days or 114,155 years worth of spinning hard drives. Let\u2019s take a look at what these hard drives have been up to.<\/p>\n","protected":false},"author":12,"featured_media":57101,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"content-type":"","footnotes":""},"categories":[7,457],"tags":[468],"class_list":["post-57031","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cloud-storage","category-hard-drive-stats","tag-b2cloud","entry"],"acf":[],"yoast_head":"\nBackblaze Hard Drive Reliability for Q1 2016<\/h2>\n
![\"Q1](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/blog-table-q1-2016-only.jpg\")
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Cumulative Hard Drive Reliability<\/a> Rates<\/h3>\n
![\"Cumulative](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/blog-table-q1-2016-cumulative-2.jpg\")
<\/a><\/p>\nOne Billion Hours of Spinning Hard Drives<\/h3>\n
![\"Q1](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/blog-table-hours-in-service.jpg\")
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\n![\"Hard](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/drive-stats-2016-q1-hours-by-manufacture.jpg\")
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\n![\"Hard](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/drive-stats-2016-q1-hours-by-size.jpg\")
<\/a><\/p>\nHard Drive Reliability by Manufacturer<\/h2>\n
\n![\"Hard](\"https:\/\/www.backblaze.com\/blog\/wp-content\/uploads\/2016\/05\/drive-stats-2016-q1-failure-by-mfg.jpg\")
<\/a><\/p>\nWhy Are There Less Than 45 Drives?<\/h3>\n
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Buying Drives From Toshiba and Western Digital<\/h3>\n
What About Using 6TB, 8TB, and 10TB Drives?<\/h3>\n
What Is a Failed Hard Drive?<\/h2>\n
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A Different Look at Hard Drive Stats<\/h2>\n