Which RAID is best…? | SQL Server Performance Forums

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Which RAID is best…?

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
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
Just in case I propose to refer this article http://www.sql-server-performance.com/rc_hardware_planning.asp that may help you with more information. _________
Satya SKJ
Moderator
SQL-Server-Performance.Com

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
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
In RAID 10 configuration, supose 3×3 (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
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.
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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