What is the formula for working out the final RAID size of a RAID 5 array knowing the number of disk and the size of each disk?

migrated from stackoverflow.com Apr 19 '11 at 22:58

This question came from our site for professional and enthusiast programmers.


Ripped from Wikipedia

Therefore, the usable capacity of a RAID 5 array is (N-1) x S(min) , where N is the total number of drives in the array and S(min) is the capacity of the smallest drive in the array.


Add the number of hard drives minus 1. Either all the drives have to be the same size, or if you use different sizes, the RAID will treat all the drives the same as it would the smaller one.

10 1TB hard drives equal 9TB of storage.

9 1TB drives and one 500GB drives is 4.5TB of storage (each 1TB is treated as a 500GB)

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.