SQL Server Performance

Which RAID is best...?

Discussion in 'Performance Tuning for Hardware Configurations' started by droesch99, Aug 11, 2003.

  1. droesch99 New Member

    We are getting some new disk, and therefore are trying to plan what, where, when, why, how... I have read that Raid10 is the best for database because it combines RAID-0 & 1. But the drawback is that it requires twice as much disk space to use it.

    We are trying to bring speed to be the foremost thing fixed, with redundancy being second. Since we backup constantly.

    What is the general feeling out there, on versions of Raid for high access databases..?

    Thanks.

    -David Roesch
    San Diego, Ca
  2. vbkenya New Member

    Yes, RAID 1 is expensive on disk space. Just use Raid 0 if performance is your primary worry. But please do BACKUPs (and verify them) as you indicated above.

    Nathan H.O.
    Moderator
    SQL-Server-Performance.com
  3. satya Moderator

  4. bradmcgehee New Member

    RAID 0 offers the best performance, but no fault tolerance. RAID 10 offers the next best performance, then RAID 1, then RAID 5. As far as I am concerned RAID 0 should not be considered, leaving RAID 10 as the only real option if you want best I/O access. Also, don't forget about the speed of the drives, the speed of the controller, and the amount of the cache on the controller, which all also play a big part in performance.

    -----------------------------
    Brad M. McGehee, MVP
    Webmaster
    SQL-Server-Performance.Com
  5. droesch99 New Member

    Thanks that was exactly what I wanted, but I have one more question.<br /><br />From what I was reading it was RAID-10 that that appears to be faster. The problem I have found is that hardly anyone supports it yet. They are saying its the same as 0+1, and from what I have read about its really not. <br /><br />Now if 0+1 will give us the perks of RAID-10, can we just have to keep an extra drive around in case one fails..? Because if a drive fails using 0+1 then the array will revert to RAID0, thereby leaving us with no fault tolerance...<br /><br /><img src='/community/emoticons/emotion-1.gif' alt=':)' /><br />-David<br /><br /><br />-David Roesch<br />San Diego, Ca
  6. Luis Martin Moderator

    In RAID 10 configuration, supose 3x3 (I mean 3 disk with mirror), if one of them is crash, no problem. More if 3 of then crash no problem.
    If one and his mirror crash at same time, now you have a problem.

    Luis Martin
  7. ykchakri New Member

    RAID 0+1 gives you best of both worlds. Over and above that there is a concept called 'spare drive' in Compaq disk arrays where you place one extra drive in the array and configure as a 'spare drive'. If one of the disks in the RAID configuration fails, the spare drive will be automatically re-built as the failed drive, thus giving you back your RAID.
  8. bradmcgehee New Member

    RAID 10 and RAID 0+1 vary between vendors somewhat. Either one is still faster than the other RAID options.

    -----------------------------
    Brad M. McGehee, MVP
    Webmaster
    SQL-Server-Performance.Com

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