Why is RAID So Important for Databases?

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added by flyingkick
2/7/2012 9:32:36 AM

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A good server design has no, or very few, single points of failure. One of the most common server component that fails, are disks. So data redundancy becomes essential to recoverability. Redundant Array of Independent/Inexpensive Disks (RAID) is a disk system that provides better fault-tolerance by making use of redundancy of disk(s).

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1 comments
dpeterson
2/7/2012 10:17:35 AM
It's actually more common to see RAID 6 than RAID 5 when dealing with larger arrays. As the number of drives in the array increases, the likelihood that a second drive will fail while already rebuilding a failed drive increases dramatically (the stress of the rebuild often triggers the failure). RAID 6 ensures that 3 drives must fail before any data loss occurs, of which the chances are much lower.
RAID 50 (mirrored arrays of RAID 5) is also a common setup as it provides increased security over RAID 10 (2 drives from both arrays must fail for all data to be lost, rather than 1 from each array in RAID 10). For databases that are critical, I would recommend RAID 50 over RAID 10, decreasing the chances that you'll need to experience downtime should a failure occur.