SQL Server Performance

What is RAID 1+0 ?

Discussion in 'SQL Server 2005 Performance Tuning for Hardware' started by NewDBA, Feb 27, 2007.

  1. NewDBA New Member

    Hi my understanding is that RAID 1+0 is first mirrored and then striped physical drives.
    And if I understood correctly I have to have 4 physical disk as minimum to accomplish RAID 1+0

    I understand the theory (I think) but I every time when I try to configure RAID Array using HP configuration utility and choose
    2 physical drives for my array - I will only have options to create RAID 0 or RAID (1+0)

    I don't think this is my "expensive" RAID that I try to create for my ldf or mdf files.

    but choosing 4 physical drive will give me the very same options - so I don't really know how to create RAID 10(1+0)

    If someone can just share own practical experiance on how I can create this type of array - it would be greatly apprectiated.

    thank you
  2. joechang New Member

    if you select 2 drives
    the vendor software program should give you RAID 0 or RAID 1 options

    if more than 2, it should give options RAID 0, 5 or 10
    10 might require an even number of drives, depending,

    read the screens more carefully
    also, it really does not matter if it says RAID 1 or 10
    your data is mirrored instead of parity checked

    it might be safe to assume the RAID vendor knew what they meant,
  3. NewDBA New Member

    i would expect that to do whatever you saing , but it is not happening
    1.
    According to HP when I choose 2 physical drive I have only 2 options in dropdown box

    RAID 0
    RAID 1+0

    2.
    If I have 3 physical drives it will tell me

    RAID 0
    RAID 5

    3.
    4 physical drives:

    RAID 0
    RAID 1+0
    -------------------------------

    I did try to read options very carefully.
  4. joechang New Member

    then RAID 1+0 with disks is just RAID 1,
    some one apparently was too lazy to add separate entries for 1 and 1+0
    don't worry about that

    that is does not support RAID 5 with disks is silly
    which controller are you on?
  5. NewDBA New Member

    It does support raid 5 - if I choose 3 or 5 disks it will let's me create raid 5

    What I am confused about : if I choose 2 phys. disk I have options for RAID0 and Raid 1+0
    and when I choose 4 disks I again have very same options : raid 0 and raid1+0.
    That 's it.

    Is that means whatever they call 1+0 raid - it is not that 1+0 raid that I am looking for? I guess so. So how do I really create RAID 10.

    Are you saing that some controllers would basically not support some raid configuration ?


    My controller is= MSA500 G2 CONTROLLER IN MA27MT4269

  6. joechang New Member

    DP NOT WORRY about whether it says: RAID 1 and RAID 1+0

    in essence, you get mirroring for data protection
    if you have 4 or more disks, you get stripping for performance

    what is stupid about the controller is that you do not have the RAID 5 option for 3 or more disks, including 4,
    there is no reason you cannot do RAID 5 on 4, or other even number of disks (>2)

    i think the person who did the program goofed
    or something

    it is amazing that this is an HP controller
    they have been doing this for a long time
  7. NewDBA New Member

    O , I see - well now I understand RAID 10.<br /><br />But what if I what to create RAID 0+1 instead of RAID 1+0 ?<br /><br />I guess I cannot.<br /><br />So truly - I can only choose between RAID 0, 1(2disks), 5(uneven number of disks)<br /> and 10 (even Number of more then 4 disks)<br /><br />No other RAIDS allowed.<br /><br />Hm-m-m-m<br /><br />Still - thank you very much ,joechang, you did helped a lot I was totally lost with this thing.<br /><img src='/community/emoticons/emotion-1.gif' alt=':)' />
  8. joechang New Member

    nitwits talk about RAID 0+1 vs RAID 1+0
    the first, in theory, implements a RAID 0 stripe, then mirrors it,
    if you lose 1 disk, the entire stripe goes down

    but the hardware is blind to this theoretical differnce between 0+1 and 1+0
    it makes no difference

    in fact, no (reputable) HW vendor should not be doing anything stupid
    so there is no point fretting whether it is 1+0 or 0+1

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