Hard Disk Bit Error Rate
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Selecting a Disk Drive: How Not to Do Research Posted January 28, 2014 By Henry Newman Send Email » More Articles » I wasn’t impressed last week when I saw Brian Beach’s blog hard drive failure rates on what disk drive to buy. I wasn’t impressed due to the
Hard Disk Repair
lack of intellectual rigor in the analysis of the data he presented. In my opinion, clearly Beach has something external hard drive else going on or lacks understanding of how disk drives and the disk drive market work. Let me preface this article with the following full disclosure: I own no stock in
Hgst
Seagate, WD, or Toshiba, nor do I have family or close friends working at any of those companies. I do not buy disk storage, as in my consulting role I am not allowed to resell hardware or software by agreement. I do know people in two of the three companies and have for years, but I have not been given free stuff ssd vs hdd nor would I take it. Basically, the only agenda I have is a comprehensive factual analysis, which in my opinion is lacking in Beach’s blog post. Let’s start at the second table in Beach’s article. I have added a few columns in green that were not part of the original, but the information in these columns can be found on the web with a bit of work, and as you will see are pretty important. Post a comment Email Article Print Article Share Articles Digg DZone Reddit Slashdot StumbleUpon del.icio.us Facebook FriendFeed Furl Let’s talk about the release data first. The oldest drive in the list is the Seagate Barracuda 1.5 TB drive from 2006. A drive that is almost 8 years old! Since it is well known in study after study that disk drives last about 5 years and no other drive is that old, I find it pretty disingenuous to leave out that information. Add to this that the Seagate 1.5 TB has a well-known problem that Seagate publicly admitted to, it is no surprise that these old drives are fa
is the best choice, ever [1]. There are cases where RAID0 is mathematically proven
Seagate
more reliable than RAID5 [2]. RAID5 should never be used for anything
Western Digital
where you value keeping your data. I am not exaggerating when I say that very often, your data wd red is safer on a single hard drive than it is on a RAID5 array. Please let that sink in.The problem is that once a drive fails, during the rebuild, if http://www.enterprisestorageforum.com/storage-hardware/selecting-a-disk-drive-how-not-to-do-research-1.html any of the surviving drives experience an unrecoverable read error (URE), the entire array will fail. On consumer-grade SATA drives that 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, https://news.ycombinator.com/item?id=8306499 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 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 rebuil
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