What's the optimal number of drives for a RAIDz2 ?

[Fritz]

I'm putting together another FreeNAS box to use as a man backup server. The Case is a LIAN LI PC-Q25 which has room for 7 3.5" drives. Is 7 drives OK for a RAIDz2 pool?

Thanks

 

[PigLover]

I'm putting together another FreeNAS box to use as a man backup server. The Case is a LIAN LI PC-Q25 which has room for 7 3.5" drives. Is 7 drives OK for a RAIDz2 pool?

Thanks

Unless you are chasing very high performance and absolutely minimal wasted space it doesn't matter a lot. For most used cases a Raidz2 of 7 drives - while not optimal - will perform just fine.

However, 'Optimal' for ZFS parity raid is always a 'power of 2' + redundant, i.e.:

Raidz: 3, 5, 9, etc. (2+1, 4+1, etc.)
Raidz2: 4, 6, 10, etc. (2+2, etc.)
Raifz3: 5, 7, 11, etc. (2+3, etc).

Obviously some of the smaller outcomes are silly (as in a 4 drive raidz2, which would have the same storage efficiency and less performance than a striped mirror of 4 drives).

Sent from my SM-G925V using Tapatalk

 

[T_Minus]

7 is fine.

@PigLover posted the generally suggested drive #s and methodology

I have RaidZ3 with 8 drives as my backup system, no issues at all !

 

[Fritz]

Thanks all. I have everything I need except the memory. I need 2 x 8gb DDR3 SODIMMS. I bought 2 a couple of months ago for 61 bucks, the same memory today is 85 bucks. I'm hoping Black Friday will have some deals. I'll stock up if the price is right.