Bye Bye RAID 5 in 2009

Discussion in 'OT Technology' started by Peyomp, Oct 22, 2008.

  1. Peyomp

    Peyomp New Member

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  2. White Stormy

    White Stormy Take that, subspace!

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    I'm using a raid 5 array :noes:
     
  3. 1999TL

    1999TL New Member

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    Im pondering if I should use raid or not in my new rig i'm about to build. debate lingers on with myself. Drives are just so big now.
     
  4. White Stormy

    White Stormy Take that, subspace!

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    just buy two 1TB+ drives and do raid 1. If a drive DID fail, you have a backup.. and if the backup has a read error and fails.. you're no worse off than if you DIDN'T have a backup solution, except you're out an extra $100-150.

    if the backup saves you.. it's probably worth more than $100-150, and that's more likely, so sounds to me like it's still the best answer
     
  5. Peyomp

    Peyomp New Member

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    Nothing wrong with using RAID 5 on a 3 disk home array or something, with 1TB disks. His point is that we are fast approaching the point that if an entire disk fails, then you will be quite likely to experience a read error during rebuild. Disks are getting bigger, but failure rates are not getting better.
     
  6. crontab

    crontab (uid = 0)

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    this woman is delirious.
     
  7. trouphaz

    trouphaz New Member

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    yeah, so what home user is using a 6+1 RAID5 parity group? i wouldn't trust home drives to that little protection. at most i'd go 3+1... though i wouldn't use RAID5 for home anyway. hard drives are cheap and RAID1 (or even RAID1+0) is much better. i can't imagine the rebuild times on many of these low end controllers would be all that great.
     
  8. deusexaethera

    deusexaethera OT Supporter

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    This is horseshit. The statistical URE rate might be one bit per 12 terabytes, but that's PER DISK, not for the whole array. In a seven-2TB-disk array with six disks operating simultaneously, you're talking about a URE rate of 1 bit per 72TB, not 12TB.

    Anyway, nobody but nobody needs 72TB of data storage, not within reason anyway. Maybe a datacenter has that much capacity, but a datacenter is also going to have far better redundancy than a home user (or even a small office like mine) anyway. We have 4TB of storage and it's half-full -- after five years of continuous operations using data files >1GB apiece, and never deleting anything.

    This is nothing more than panic-mongering.
     
  9. Peyomp

    Peyomp New Member

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    This is interesting. What makes you think the rate wouldn't hold across disks? Wouldn't you expect that if you had 1,000,000,000,000 disks, and read 1 byte off each that you would get one bad read?
     
  10. Limp_Brisket

    Limp_Brisket New Member

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    oh, i didn't even notice it was a woman. at least now i can discount everything i read.

    edit - it's just a man named Robin, you fooled me!
     
  11. deusexaethera

    deusexaethera OT Supporter

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    I say that because while the average number of reads between failures is 12TB, that doesn't mean that the likelihood of failure is identical from Read #1 to Read #n. The MTBF only means that after reading 12TB of data, you have a 50% chance of having suffered one URE; the actual likelihood of failure at any given point in time is described by a hyperbolic curve that starts at 0% at Read #1, crosses the 50% mark at Read #12billion, and trends towards 100% as it approaches Read #Infinity.

    Why does that matter? Because if the likelihood of failure per disk starts out infinitesimal and increases as time and wear increase, then that means that 6 disks reading 2TB of data each will not progress as far along the failure-probability curve as a single disk reading 12TB of data would -- the wear is split across multiple disks, so each disk suffers substantially less wear during the rebuild than a single disk would if it had read the same amount of data all by itself. Likewise, the failure-probabilities for all of the drives added together will not equal the failure-probability of a single drive that had read the same amount of data all by itself.
     
    Last edited: Oct 23, 2008
  12. deusexaethera

    deusexaethera OT Supporter

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    All the Robins I've met were women. Is there a pic of the author anywhere?
     
  13. Limp_Brisket

    Limp_Brisket New Member

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    that's his picture in the top right of the page. i thought it was just a stock photo :mamoru:
     
  14. lowfat

    lowfat 24/Mac/SciFi/PC Crew OT Supporter

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    That article is complete bullshit.

    RAID =! backup. You are a moron if you leave all your critical data on one computer without a backup.
     
  15. Supernaut

    Supernaut New Member

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    Oh fuck, first sign of the apocalypse. BRB, gonna buy some ammo.
     
  16. trouphaz

    trouphaz New Member

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    [​IMG]
    Here is a Robin that is a man. It is this guy's son.

    [​IMG]
     
  17. White Stormy

    White Stormy Take that, subspace!

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    Robin Leach
    [​IMG]
     
  18. Limp_Brisket

    Limp_Brisket New Member

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    don't forget robin williams
     
  19. deusexaethera

    deusexaethera OT Supporter

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    I think we might be getting a little off track.

    Good point about Robin Williams though, I forgot about him.
     
  20. trouphaz

    trouphaz New Member

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    actually, i think it has been decided. the bitch who wrote that article is an idiot.
     

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