Linked by Thom Holwerda on Fri 18th Sep 2009 13:40 UTC, submitted by Robert Escue
This is an article which discusses the increase in storage capacity while performance and hard error rates have not improved significantly in years, and what this means for protecting data in large storage systems. "The concept of parity-based RAID (levels 3, 5 and 6) is now pretty old in technological terms, and the technology's limitations will become pretty clear in the not-too-distant future â" and are probably obvious to some users already. In my opinion, RAID-6 is a reliability Band Aid for RAID-5, and going from one parity drive to two is simply delaying the inevitable."
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Member since:2006-01-19
I thought modern raid systems used error correcting codes, which means even random bad bits did not irreversible damage the data if there was a drive failure.
What am I missing?
PS. My days of studying raid-systems was over a decade ago.
What am I missing?
PS. My days of studying raid-systems was over a decade ago.
True if you are running a system that actually does checksumming, like NetApp or ZFS. But many lower end systems do not. Even if you have checksumming and so can detect, say, a flipped bit in a sector that you need for reconstructing a stripe, you would need a second parity stream to reconstruct the stripe (one for the dead disk's missing sectors, one for the "bad" sector from the otherwise "good" disk). So IMHO multiple-parity raid plus checksumming is a great idea, if you have to use parity raid that is.
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Member since:
2005-07-06
I thought modern raid systems used error correcting codes, which means even random bad bits did not irreversible damage the data if there was a drive failure.
What am I missing?
PS. My days of studying raid-systems was over a decade ago.