Unraid Parity Size

[Nov845]

How much parity would you recommend for 108TB total HDD capacity? I have four 10TB, eight 6TB, and five 4TB drives. One 10TB drive would be a little over 9%.

[LIGISTX]

9 minutes ago, Nov845 said:

How much parity would you recommend for 108TB total HDD capacity? I have four 10TB, eight 6TB, and five 4TB drives. One 10TB drive would be a little over 9%.

I wouldn’t do any less than 2 drives, and the way unraid works, they have to be the largest size drives. So…. 2 10TB’s it is. Technically that is still a bit risky, since 2/17 drives are doing parity duty. But that is my recommendation. 

[Kilrah]

32 minutes ago, Nov845 said:

One 10TB drive would be a little over 9%.

That's not how parity works in unraid, it's not based on a percentage of capacity.

 

Only things that matter is that:

- Your parity drive size defines the largest size of data disk that you can use

- The number of parity drives is the number of drives that can fail simultaneously without losing data

 

With that many drives the probabilty of some failing starts getting high, so I'd run 2 parity drives. Size of the parity drives is then chosen based on whether you expect to later install bigger drives or not, but in your case 10TB is the minimum size you can use.