differences between raid 1+0/0+1
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Thread: differences between raid 1+0/0+1

  1. #1
    Join Date
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    Hello,
    I have read some docs explaining me each raid levels but I am still a bit confused between raid 1+o vs 0+1.I know oracle wants raid o+1 for systems/rdo/rbs but i couldnt figure the arguement between 1+0 vs 0+1. Can somebody in laymen's term explain me the difference??

    thanks
    Jigar
    "High Salaries = Happiness = Project Success."

  2. #2
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    Hi Lakhani,
    it is as simple as it.
    RAID 0+1 : “Stripe First, Then Mirror What You Just Striped”.
    RAID 1+0 : “Mirror First, Then Stripe Over What You Just Mirrored”.
    Do you want some more details on it??
    Hope it helps, All The Best
    Sandy
    "Greatest Rewards come only with Greatest Commitments!"

  3. #3
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    RAID 1+0 is mirroring and then striping. RAID 0+1 is striping then mirroring.

    For example, say you have four disks, sd0, sd1, sd2, sd3. RAID 1+0 would mirror disks sd0 to sd2 and sd1 to sd3. You would then create a logical volume striping the data across the two mirrored devices.

    In RAID 0+1, you would create a stripe on sd0 and sd1, a stripe on sd2 & sd3, and create a logical mirror between the two striped volumes.

    RAID 1+0 and 0+1 have similar performance. However, RAID 1+0 has more sustained redundancy. In the two examples above, lets assume sd1 goes bad. In the RAID 1+0, sd0 and sd2 are still mirrored. In the RAID 0+1, you are left with no redundancy.
    Jeff Hunter
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  4. #4
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    Marist,
    so if RAID 0+1 has no redundency then why does Oracle recommend it?
    "High Salaries = Happiness = Project Success."

  5. #5
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    Originally posted by jlakhani
    Marist,
    so if RAID 0+1 has no redundency then why does Oracle recommend it?
    Whoa. RAID 0+1 does have redundancy. The redundancy is sacrificed when a disk goes bad which renders the stripe bad. Most arrays that have 0+1 capability have the capability to detect a bad drive, fail it, and substitute a hot spare. While the hot-spare is resyncing, you don't have any redundancy. Once the stripe is back to normal, you have your redundancy again. When a disk goes bad, you have mabye two hours where the stripe is vunerable.

    In a 1+0 system, up to 1/2 of your disks can go bad before you lose all your redundancy.
    Jeff Hunter
    marist89@yahoo.com
    http://marist89.blogspot.com/
    Get Firefox!
    "I pledge to stop eating sharks fin soup and will not do so under any circumstances."

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