Home > raid 5 > sata bit error rate raid 5

Sata Bit Error Rate Raid 5

is the best choice, ever [1]. There are cases where RAID0 is mathematically proven raid 5 ure calculator more reliable than RAID5 [2]. RAID5 should never be used for anything unrecoverable read error rate where you value keeping your data. I am not exaggerating when I say that very often, your data why not to use raid 5 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 dell raid 5 is no longer recommended 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,

What Happens If The Array Experiences A Ure During The Rebuild Process

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 rebuild.[1] http://www.smbitjournal.com

WeirdCrap (12) Archives March 2015 November 2014 September 2011 February 2010 October 2009 August 2009 May 2009 February 2009 December 2008 November 2008 October 2008 September 2008 August 2008 June 2008 May 2008 April 2008 March

Hard Drive Ure

2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 June 2007 raid 10 ure May 2007 April 2007 March 2007 February 2007 January 2007 SATA Unrecoverable errors and how that impactsRAID Posted on October 28, raid 5 is no longer recommended for any business critical information on any drive type 2008 by subnetmask255x4 You may have been reading lately about the END OF THE WORLD… oh wait, sorry, just how RAID-5 is completely screwed over the next few months. Well, I am here to try and https://news.ycombinator.com/item?id=8306499 help shed some light on the situation, and hopefully, not spread some crap on it. So, what are unrecoverable errors? First, some clarification. These types of errors are seemingly referred to with 3 different names: Bit Error Rate (BER) Unrecoverable Bit Error (UBE) Unrecoverable Read Error (URE) However, these all refer to the same problem, in that over time, drives will simply fail to see data due to some kind of https://subnetmask255x4.wordpress.com/2008/10/28/sata-unrecoverable-errors-and-how-that-impacts-raid/ error. Doesn't matter what the cause of this error is, most vendors don't go into that kind of detail. Now, these error rates occur between 1 in 10^14 bits of data, up to 1 in 10^16 bits of data. So, what does that mean: Error Ratehow many bits is that?how many bytes?Real World numbers 10^14 bits100,000,000,000,00012,500,000,000,00012.5TB 10^15 bits1,000,000,000,000,000125,000,000,000,000125TB 10^16 bits10,000,000,000,000,0001,250,000,000,000,0001.25PB This means that a drive with an Error Rate of 10^14 bits, will see an error around once every 12.5TB read from it. If you have a 2TB drive, you write 2TB to it, and then you fully read that, just over 6 times, then you will run into one read error, theoretically speaking. If you have a 1TB drive, and blah blah, it will take over 12 times to run into a read error. The numbers go up by an order of magnitude (ahem, multiply the number by 10) for each 10^x improvement you make. A 1TB drive with an error rate of 10^15 bits, will take 125 times to run into a read error; an error rate of 10^16 bits will take 1,250 full drive reads to run into one error. The RAID problem The problem becomes a concern as you mix together two issues: 1) drives approaching 2TB each. 2)

Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow http://serverfault.com/questions/192995/raid-5-with-big-sata-disks-do-or-dont the company Business Learn more about hiring developers or posting ads with us Server Fault Questions Tags Users Badges Unanswered Ask Question _ Server Fault is a question and answer site for system and network administrators. Join http://www.techrepublic.com/blog/the-enterprise-cloud/how-to-protect-yourself-from-raid-related-unrecoverable-read-errors-ures/ them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top RAID 5 with big SATA raid 5 disks. Do or don't? up vote 5 down vote favorite 2 Is it sane to build a machine with RAID 5 expecting to hold around 5 Tb (and able to grow) with 1.5 or 2 Tb SATA II disks? It will be used as audio and documents storage. I already have chosen a chassis with 16 3.5" hard drive bays. Now I'm thinking about what to put on those bays. Pros I see: Cheaper raid 5 is per Tb Greater extensibility per chassis (3 times max capacity using 1.5 vs. 0.5) It's the cons I'm wondering about. I expect using big disks to be slower, but is this really the case? I don't know about failure rates between small and big drives, are big ones expected to fail more often? So, two questions: What are the cons of building a 5Tb RAID5 with big disks? Any particular drive model you'd recommend for either big (2Tb) or small (0.5Tb)? raid hard-drive raid5 share|improve this question asked Oct 20 '10 at 14:40 Vinko Vrsalovic 1,2031319 1 Bigger drives != slower performance. The drive platters aren't physically bigger, they have more platters. Each surface of each platter normally has it's own read\write head (if each surface of the platter is used for data storage) so access times should be roughly equivalent to smaller drives. –joeqwerty Oct 20 '10 at 15:21 1 On the contrary, I would expect bigger drives to be faster than smaller drives. All else being equal (rotational rate, number of heads, physical size), a larger drive will have a greater bit density than a smaller drive, which implies that its read/write rate will be higher. –Steven Monday Oct 20 '10 at 15:47 It depends what you mean by 'big' and 'fa

United States Australia United Kingdom Japan Newsletters Forums Resource Library Tech Pro Free Trial Membership Membership My Profile People Subscriptions My stuff Preferences Send a message Log Out TechRepublic Search GO Topics: CXO Cloud Big Data Security Innovation Software Data Centers Networking Startups Tech & Work All Topics Sections: Photos Videos All Writers Newsletters Forums Resource Library Tech Pro Free Trial Editions: US United States Australia United Kingdom Japan Membership Membership My Profile People Subscriptions My stuff Preferences Send a message Log Out Data Centers How to protect yourself from RAID-related Unrecoverable Read Errors (UREs) Seeing an Unrecoverable Read Error (URE) during a RAID rebuild can ruin your entire day. Scott Lowe talks about UREs and how you can avoid falling victim to this silent threat. By Scott Lowe | in The Enterprise Cloud, November 15, 2009, 8:36 PM PST RSS Comments Facebook Linkedin Twitter More Email Print Reddit Delicious Digg Pinterest Stumbleupon Google Plus If you are ever rebuilding a RAID system, Unrecoverable Read Error (URE) is one term you don't want to learn about the hard way. As the name implies, a URE makes for a really bad day, as it can stop a RAID rebuild in its track, essentially making the entire RAID volume unusable. I won't go into a lot of detail about the "why" behind what causes a URE because many other very smart people have already done a good job of explaining it. (Admittedly, some of the warnings might be sensationalist, and there seems to be some confusion on terminology, but do your own math to see if you might have a serious problem.) What I will do is provide you with tips on how to make sure that you don't fall victim to these errors. 1. Don't use RAID 5 if you plan to use large nonenterprise-grade SATA disks. When it comes to reliability, enterprise grade disks are generally at least one order of magnitude more reliable than their nonenterprise counterparts. If you believe what has been written about UREs, as the size of disks increases and as more disks are added to RAID 5 arrays, the likelihood of total data loss across the entire RAID volume begins to get into dangerous territory. If you're trying to build a 14 disk RAID array using 1.5TB or 2TB SATA disks you bought at Best Buy, consider using

Related content

repair raid 5 error
Repair Raid Error p associated with the member disks operator error or controller failure RAID failures RAID can fail due to any of the mentioned above reasons However RAID is a redudant array which means it can raid disk failure survive failure of one of the member disk If failure of your RAID affects p Raid Disk Failure Recovery p only one member disk then you are lucky and can easily get your data back In case of multiple disk failures p Raid Hard Drive Failure p there is zero chance of recovering the array data Failure of one of

unrecoverable read error raid 5
Unrecoverable Read Error Raid p the unrecoverable data error in which he points out that while disk manufacturers quoted Bit Error Rates BER for hard disks are typically - or - SSD BERs range from - for consumer drives to - for hardened enterprise drives Below the fold a raid ure calculator look at his analysis of the impact of this difference of up to orders of what is an unrecoverable read error ure magnitude When a disk in a RAID- array fails and is replaced all the data on other drives in the array must be read to p