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9 Replies Latest reply: Oct 26, 2013 10:22 PM by user312846 RSS

RAID LEVEL FOR OCR AND VOTING DISK

user312846 Newbie
Currently Being Moderated


Hi All,

 

We are in the process og Oracle 11g Installation with ASM keeping OCR and VD in ASM. For external redundancy whats the best raid level for OCR and Voting Disk.

 

 

Thanks in Advance

  • 1. Re: RAID LEVEL FOR OCR AND VOTING DISK
    MahirM.Quluzade Guru
    Currently Being Moderated

    Hi,

     

    It is good practice, you are using ASM diskgroups for OCR and VOTE files.

    I think, RAID 1+0 is the best for storage RAID level for ASM.

     

    What is level  now?

     

    Regards

    Mahir M. Quluzade

  • 2. Re: RAID LEVEL FOR OCR AND VOTING DISK
    BillyVerreynne Oracle ACE
    Currently Being Moderated

    user585870 wrote:

     

    We are in the process og Oracle 11g Installation with ASM keeping OCR and VD in ASM. For external redundancy whats the best raid level for OCR and Voting Disk.

    Best is kind of subjective.

     

    My preference is for RAID10, and if that not available, RAID5. Or alternatively, no RAID at all and using normal and high redundancy via ASM. (currently using all these in a number of different RAC configs)

  • 3. Re: RAID LEVEL FOR OCR AND VOTING DISK
    user312846 Newbie
    Currently Being Moderated

    Thinking of 10...

     

    so thought of getting expert advice

  • 4. Re: RAID LEVEL FOR OCR AND VOTING DISK
    BillyVerreynne Oracle ACE
    Currently Being Moderated

    Oracle's recommendation (in a number of support notes covering RAC cookbooks and best practises), is SAME - Stripe And Mirror Everything.

     

    So 1st prize is definitely RAID10 - but likely expensive when dealing with large databases.

  • 5. Re: RAID LEVEL FOR OCR AND VOTING DISK
    user312846 Newbie
    Currently Being Moderated

    Thank you..

     

    For OCR & VD its not that much space consuming...so will go with RAID 10

  • 6. Re: RAID LEVEL FOR OCR AND VOTING DISK
    tmbeetz Explorer
    Currently Being Moderated

    Hi,

     

    oracle say SAME "Stripe And Mirroring Everything". If your raid-controller is good, then build RAID-5 or RAID-6 works fine.

     

    Best regards

    thomas

  • 7. Re: RAID LEVEL FOR OCR AND VOTING DISK
    BillyVerreynne Oracle ACE
    Currently Being Moderated

    It is not an issue whether the raid-controller is good or bad. The issue is performance - what are the overheads and how does it affect latency? As RAID5 requires a checksum calculation on every I/O write, this is a large overhead. If that checksum calculation is done serially, then the writer needs to wait for checksum-calc-and-write to complete too. If instead the writer writes to a storage server cache (instant return of I/O write call), followed by the storage system doing the checksum-calc-and-write as part of a lazy write to disk,  then the overhead does not exist from the writer's perspective.

     

    RAID5 and RAID6 can kill database performance.

  • 8. Re: RAID LEVEL FOR OCR AND VOTING DISK
    Levi-Pereira Guru
    Currently Being Moderated

    > For external redundancy whats the best raid level for OCR and Voting Disk.

     

    If you are concerned only about store OCR and Voting Disk, from my point of view you can use any RAID (except  0) that will not make difference about performance.

    This is because OCR and Voting Disk has low I/O activity.

    But you must avoid  place Voting Disk in a overloaded array because a Node Fencing  can happens if a node not being able to ping the cluster voting files or  occurs I/O starvation which makes generally ping operations not possible in a timely manner.

    e.g Placing voting disk in a array where redo/datafile has high I/O activity, this can cause a problem and should be avoided.


    I recommend you create a small diskgroup with Normal Redundancy to store only Voting Disk and OCR  using 3 Luns preferable each Lun in different array.

    Two reason:

    1 - Separate clusterware files from database files, this prevents human errors or management issues.

    e.g Cloning a Diskgroup (to Clone a database) using third-party tools, add or remove luns of diskgroup to change size or migration, drop database Files manually on ASM, etc.

    2 - Multiplexing voting disk in a 3 different Luns (Normal Redundancy) you can protect clusterware files (voting disk, ocr and asmspfile) against logical/physical corruption. Using one Voting disk you are unprotected against this type of failures.


    My point here limits on Clusterware World (what means which not involves Oracle RAC)


    Billy has a good point, I agree with your points regarding about database perfomance and RAID.





  • 9. Re: RAID LEVEL FOR OCR AND VOTING DISK
    user312846 Newbie
    Currently Being Moderated

    Thank you Levi for sharing your ideas on this.

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