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mirror in storage pool RRS feed

回答

  • Hi,

    I contacted related department about this quesiton and got the answer. Hope it could help:

    Pool requires a quorum of 50% plus drives to be present to survive.

    with 3 way mirror - we have a guarantee of surviving 2 disk failure.

    Maintaining the above requirements and providing the guarantee - mandates us to have minimum 5 disks in pool. As if we loose 2, we still have 3 in the pool (>50%) for pool to maintain it's quorum.


    TechNet Subscriber Support in forum |If you have any feedback on our support, please contact tnmff@microsoft.com.

    • 回答としてマーク MedicalSMicrosoft contingent staff 2012年12月24日 1:51
    • 回答としてマークされていない ZWJ 2012年12月24日 2:13
    • 回答としてマーク ZWJ 2012年12月24日 3:18
    2012年12月24日 1:09
  • This article gives me some clues:

    http://www.bleepingcomputer.com/tutorials/how-to-configure-storage-spaces-windows-8/

    Three-way mirroring is similar to two-way mirroring, but requires 5 drives. This storage process provides hardware protection in the event that two drives fail at the same time.

    Now I can understand.

    the 50%+ requirement is only for three-way mirror. Two-way mirror is not limited.

    All are clear now. 

    • 回答としてマーク ZWJ 2012年12月24日 3:18
    2012年12月24日 3:18

すべての返信

  • Why would you be using a storage pool for mirroring or various types of RAID? i have seen this a few times people talking about configuring things in a storage pool?

    surely this should be done by hardware a raid controller? or even by the motherboard software as a last resort??

    2012年12月14日 11:43
  • Hi ZWJ,

    I suspect that this is very much like RAID-10 if you understand the principles of RAID-10, in that you can have multiple drives in a RAID-10 and lose up to half of the drives in the entire array.  So if you have 6 drives in the array, then you can in theory lose up to 3 drives before the array becomes unusable.

    That is my theory anyway!  I hope that helps...


    Robert Milner | Website: http://www.remilner.co.uk | Twitter: @robm82

    2012年12月14日 12:09
  • in this article:

    http://blogs.technet.com/b/yungchou/archive/2012/08/31/windows-server-2012-storage-virtualization-explained.aspx

    it says:

    • Mirror - This is a mirror set without striping or parity by duplicating data on two or three disks, similar to RAID 1. It increases reliability with reduced capacity. This configuration requires at least two disks to protect data from a single disk failure, or at least five disks to protest from two simultaneous disk failure.

    why at least five disks to protest from two simultaneous disk failure? if all disks stores the same data, we should be able to bare 4 disk faiure, right?

    That's the way MS had implemented storage pools... In general yes, for RAID10 you need 4 drives and not 5.

    StarWind iSCSI SAN & NAS

    2012年12月15日 15:51
  • Its for the max storage space usage. If you set a 5-way mirror then only 20% storage space is available.

    As if you prefer a 5-way mirror, as Robert said you could simply config a RAID.


    TechNet Subscriber Support in forum |If you have any feedback on our support, please contact tnmff@microsoft.com.

    2012年12月19日 12:51
  • Yes, Raid 0+1 just needs 4 disks not 5. So does the document write wrongly?
    2012年12月20日 8:51
  • Hi,

    I contacted related department about this quesiton and got the answer. Hope it could help:

    Pool requires a quorum of 50% plus drives to be present to survive.

    with 3 way mirror - we have a guarantee of surviving 2 disk failure.

    Maintaining the above requirements and providing the guarantee - mandates us to have minimum 5 disks in pool. As if we loose 2, we still have 3 in the pool (>50%) for pool to maintain it's quorum.


    TechNet Subscriber Support in forum |If you have any feedback on our support, please contact tnmff@microsoft.com.

    • 回答としてマーク MedicalSMicrosoft contingent staff 2012年12月24日 1:51
    • 回答としてマークされていない ZWJ 2012年12月24日 2:13
    • 回答としてマーク ZWJ 2012年12月24日 3:18
    2012年12月24日 1:09
  • Thank you for your confirmation.

    But I do not think this explaination is  very accurate.

    Considering a simplist situation: 2-way mirror with only two disks —— If one disk fails, we can still access the data, right? But it is 50% not 50%+.

    How will you explain this? an exception?


    • 編集済み ZWJ 2012年12月24日 2:18
    2012年12月24日 2:17
  • This article gives me some clues:

    http://www.bleepingcomputer.com/tutorials/how-to-configure-storage-spaces-windows-8/

    Three-way mirroring is similar to two-way mirroring, but requires 5 drives. This storage process provides hardware protection in the event that two drives fail at the same time.

    Now I can understand.

    the 50%+ requirement is only for three-way mirror. Two-way mirror is not limited.

    All are clear now. 

    • 回答としてマーク ZWJ 2012年12月24日 3:18
    2012年12月24日 3:18
  • Per my test in 2012, if the pool has less than five physical disks and you choose mirror when creating a virtual disk, it will automatically create a 2-way mirror virtual disk. If the pool has five or more physical disks and you choose mirror when creating a virtual disk, you will get a page prompting you to choose 2-way mirror or 3-way mirror. So if the pool has less than five disks, you will have no chance to setup a 3-way mirror.


    • 編集済み Tim Quan 2012年12月28日 6:03
    2012年12月28日 6:02
  • Per my test in 2012, if the pool has less than five physical disks and you choose mirror when creating a virtual disk, it will automatically create a 2-way mirror virtual disk. If the pool has five or more physical disks and you choose mirror when creating a virtual disk, you will get a page prompting you to choose 2-way mirror or 3-way mirror. So if the pool has less than five disks, you will have no chance to setup a 3-way mirror.



    Correct.  Because of the logic behind the quorum, you need at least 5 disks to make a 3-way mirror.

    Robert Mitchell Senior Support Escalation Engineer Microsoft Corp.

    2012年12月31日 20:31
  • So the capacity of three way mirror?
    2017年4月17日 1:16