RAID System with more than 2 parity disks

[Daniel_00000]

I know, that it is possible to have a RAID system with 2 parity disks (RAID 6). What I was curious to find out is, if it is possible to have more than 2 parity disks in one RAID system. Apparently, no one knows how that could be accomplished, so I started trying myself.

 

After a lot of mathematical research, I created an algorithm, that allows a RAID system to have basically an unlimited amount of parity disks.

I would like to sell this algorithm to hp, since they could create new RAID controllers and Software Solutions with it. 

 

[Personal Information Removed]

[DGroves]

Raid in general is not recommended with todays large capacity disks (over 6TB),  as the time to rebuild and the chance of a parity error on rebuild increases dramatically with large capacity drives

you can use dual ported SAS disks, with each SAS link on the disk connected to a different raid controller for high availability/redundancy

having more than two parity drives per array is not done as it increases the cost of the array (parity drives don't store data) and does not make the array more reliable and adding a second parity drive slows the array down so trying to add more parity drives to a array is counter productive

A RAID 6 array can recover from two simultaneous disk failures., this is  what is considered a reasonable balance between cost/speed/reliability

RAID 60 is similar to RAID 50. The main difference is that RAID 60 requires 8 drives and contains two RAID 6 arrays. This configuration provides enhanced data protection because it uses two sets of parity data and the striping provides a performance boost.

[Daniel_00000]

Hello  DGroves

thanks so much for taking the time to respond to my post. I happen to disagree with a couple of things.

“...having more than two parity drives per array is not done as it increases the cost of the array (parity drives don't store data) and does not make the array more reliable…”

It absolutely does make it more reliable, that is the point of having a parity set.

Let’s say you have an array with 3 disks, one of them being a parity disk, and the probability that 1 Disk fails in one year is 1% (just a guess, what I am about to demonstrate is true regardless of what the actual probability is). 

Using the principles of binomial probability distribution, we can calculate that the probability of a loss of data in this configuration is: 0,0298%

Now if we were to add 1 more parity disk, the probability of a loss drops to 0,000397%

The more parity disks in a RAID system, the lower the risk of data loss.


“....A RAID 6 array can recover from two simultaneous disk failures….”

Yes, exactly. This is what I've been talking about. And I managed to develop a method, that allows the user to recover an unlimited number of simultaneous disk failures.

“, this is what is considered a reasonable balance between cost/speed/reliability”

No, you can actually increase reliability while also cutting down the cost.

For example: if you have 3 data disks and 2 parity disks (making the same assumptions as above) the probability of experiencing a loss of data in one year is:

0,0009851%

If you got this setup twice, you could unite all disks to a single RAID with 6 data disks with 3 parity disks. We went from 10 disks to 9, cutting down on hardware expenses, while making your RAID safer. We can now completely tolerate a 3-disk failure. In the set-up, we could only tolerate a 3 disk failure as long as the distribution of failed disks was favorable to us. The probability of data loss is now: 

0,000121%

Untilzing my algorithm big companies that offer cloud storage solutions, could save millions of dollars in hardware expenses, while simultaneously increasing their data safety.