Hdd Bit Error Rate
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is the best choice, ever [1]. There are cases where RAID0 is mathematically proven more reliable than RAID5 [2]. RAID5 should never be used unrecoverable read error rate for anything where you value keeping your data. I am not exaggerating when I hard drive failure rates say that very often, your data is safer on a single hard drive than it is on a RAID5 array. Please let raid 5 ure calculator that sink in.The problem is that once a drive fails, during the rebuild, if any of the surviving drives experience an unrecoverable read error (URE), the entire array will fail. On consumer-grade SATA drives that
Raid 10 Ure
have a URE rate of 1 in 10^14, that means if the data on the surviving drives totals 12TB, the probability of the array failing rebuild is close to 100%. Enterprise SAS drives are typically rated 1 URE in 10^15, so you improve your chances ten-fold. Still an avoidable risk.RAID6 suffers from the same fundamental flaw as RAID5, but the probability of complete array failure is pushed back one level, making RAID6 hard disk repair with enterprise SAS drives possibly acceptable in some cases, for now (until hard drive capacities get larger).I no longer use parity RAID. Always RAID10 [3]. If a customer insists on RAID5, I tell them they can hire someone else, and I am prepared to walk away.I haven't even touched on the ridiculous cases where it takes RAID5 arrays weeks or months to rebuild, while an entire company limps inefficiently along. When productivity suffers company-wide, the decision makers wish they had paid the tiny price for a few extra disks to do RAID10.In the article, he has 12x 4TB drives. Once two drives failed, assuming he is using enterprise drives (Dell calls them "near-line SAS", just an enterprise SATA), there is a 33% chance the entire array fails if he tries to rebuild. If the drives are plain SATA, there is almost no chance the array completes a rebuild.[1] http://www.smbitjournal.com/2012/11/choosing-a-raid-level-by...[2] http://www.smbitjournal.com/2012/05/when-no-redundancy-is-mo...[3] http://www.smbitjournal.com/2012/11/one-big-raid-10-a-new-st... Twirrim 764 days ago Note that the 10^14 figure is only what the HDD mfgs publish, and it has been the same for something like a decade. It's a nice, safe, conservative figure that seems impressively high to IT Directors and accountants, and yet it's low enough that HDD mfgs can easily fall back on it as a reason why
Backing Up | Backblaze Bits Be the first to know! Subscribe today to receive Backblaze blog post emails automatically! This field is required Join No Spam. Unsubscribe any time. Follow us: Cloud backup. Mac or PC. Unlimited data. $5/month. And you can try it for free today. hdd ure What Can 49,056 Hard Drives Tell Us? Hard Drive Reliability Stats for Q3 2015 October 14th, 2015
Hgst
As of the end of Q3 2015, there were 50,228 drives spinning in the Backblaze datacenter. Subtracting boot drives, drive models with less than 45 drives
Dell Raid 5 Is No Longer Recommended
and drives in testing systems, we are publishing data on 49,056 hard drives spread across 26 different models, varying from 1.0TB to 8.0TB in size. What’s New for the Q3 2015 Results? In this edition, we are publishing the data on our https://news.ycombinator.com/item?id=8306499 1TB drives for the first time. The data was always available in the data files we publish on our Hard Drive Data web page, but now we’re reporting the data here too. We are also going to include “Average Drive Age” for each model and we’ll summarize the data by manufacturer size as well. Hard Drive Failure Rates Let’s start by breaking down the drives by size and comparing them over time: There’s a lot going on in the chart above, here are a few things https://www.backblaze.com/blog/hard-drive-reliability-q3-2015/ to help out: The 2013, 2014, and 2015 failure rates are cumulative for the given year. In the case of 2015 that is through Q3 (September). If the failure rate is listed as 0.00% there were drives in use, but none of the drives failed during that period. If the failure rate is blank, there were no drives in use during that period. The “All Periods” failure rates are cumulative for all data (2013-Q3 2015). The “Max # in Service” column is the maximum number of drives ever in service for the given hard drive model. The “Avg Age (Months)” column is the average age of all the hard drives of the given hard drive model. This is based on SMART 9 data. If the “Avg Age (Months)” data is 0.0, the given drive model was not in service during 2015 making the value difficult to compute. (We’ll try to figure out a better way to compute this value by the next report.) The HGST (*) model name - we’ve been asked to use HGST in place of Hitachi and we are honoring that request, but these drives report their model as Hitachi and are listed as such in the data files. The Low Rate and High Rate are the boundaries for the confidence interval for the failure rate listed. If the chart is too much data all at once, you can download a ZIP file that when unzipped contains a Microsoft Excel file of the data from the chart. Then you can par
The PC Guide Tip Jar. Visa/MC/Paypal accepted. View over 750 of my fine art photos any time for free at DesktopScenes.com! [ The PC Guide http://www.pcguide.com/ref/hdd/perf/qual/specRates-c.html | Systems and Components Reference Guide | Hard Disk Drives | Hard https://www.microsoft.com/en-us/research/publication/empirical-measurements-of-disk-failure-rates-and-error-rates/ Disk Performance, Quality and Reliability | Hard Disk Quality and Reliability | Hard Disk Quality and Reliability Specifications ] Error Rates
Ack! Hard disk errors! Surely, "this is the stuff that PC nightmares are made of". :^) Fortunately, true errors are rarely encountered when using hard disks. To help users understand error rate better the rate at which errors will occur with a hard disk, manufacturers provide anywhere from one to several error rate specifications. The most common error rate spec is the drive's unrecoverable error rate, which is usually specified as "<1 in 10N bits", where "N" is usually between 12 and 15. "Unrecoverable" means that the drive is unable to use its error-correcting code, retries hdd bit error or other techniques to recover from the error in reading the disk and thus properly recreate the data. If "N" is 14, then that means this will occur every 100 trillion (100,000,000,000,000) bits read from the disk. Not too shabby. :^) In fact, drives usually have several different error rate specifications; they are just usually not put into the short data sheets commonly distributed by hard disk manufacturers. In fairness, unrecoverable errors are the most important ones, but there are also specifications for recoverable errors, errors recovered after multiple reads and so on. To find these, you generally need to download the product manual for the drive or contact the manufacturer's technical support department. For a full explanation of these various errors and what they mean, see this full discussion of errors and error recovery. Error rate specifications are typically used to compare drives. Within the same general class of drive there are usually relatively few differences between manufacturers. The biggest difference in error rate can be seen by comparing newer drives to older ones--newer drives are usually significantly better despite pushing the design envelope with higher speed andWindows games Windows phone games Entertainment All Entertainment Movies & TV Music Business & Education Business Students & educators Developers Sale Sale Find a store Gift cards Products Software & services Windows Office Free downloads & security Internet Explorer Microsoft Edge Skype OneNote OneDrive Microsoft Health MSN Bing Microsoft Groove Microsoft Movies & TV Devices & Xbox All Microsoft devices Microsoft Surface All Windows PCs & tablets PC accessories Xbox & games Microsoft Lumia All Windows phones Microsoft HoloLens For business Cloud Platform Microsoft Azure Microsoft Dynamics Windows for business Office for business Skype for business Surface for business Enterprise solutions Small business solutions Find a solutions provider Volume Licensing For developers & IT pros Develop Windows apps Microsoft Azure MSDN TechNet Visual Studio For students & educators Office for students OneNote in classroom Shop PCs & tablets perfect for students Microsoft in Education Support Sign in Search Microsoft Search Research Research Research Home Research areas Algorithms Artificial intelligence and machine learning Computer systems and networking Computer vision Data visualization, analytics, and platform Ecology and environment Economics Graphics and multimedia Hardware, devices, and quantum computing Human-centered computing Mathematics Medical, health, and genomics Natural language processing and speech Programming languages and software engineering Search and information retrieval Security, privacy, and cryptography Social Sciences Technology for emerging markets Products & Downloads Programs & Events Academic Programs Events & Conferences People Careers About About Microsoft Research blog Asia Lab Cambridge Lab India Lab New England Lab New York City Lab Redmond Lab Applied Sciences Lab Research areas Algorithms Artificial intelligence and machine learning Computer systems and networking Computer vision Data visualization, analytics, and platform Ecology and environment Economics Graphics and multimedia Hardware, devices, and quantum computing Human-centered computing Mathematics Medical, health, and genomics Natural language processing and speech Programming languages and software eng