Optimal number of disks for RAID10

[Jaan]

Didn't want to put this in server 2016 as it isn't 2016 specific per say.

 

We currently haver a hyper-v host with a raid 10 volume (4 disks) and a replica server of the same spec.

 

We just had a disk fail, not a biggie no performance hit, just a notification to say it isn't right. This got me thinking.... we are thinking of going S2D in the future but don't have the money for more nodes (at the mo). So we are continuing with two identical hyper-v hosts with replica and raid 10 for the VMS.

 

We currently have 4 500gb in RAID 10 so 1tb usable. Our server can support 24 disks, and we were thinking that more, lower capacity disks make more sense from a cost a i/o perspective for a hyper-v host. How does RAID 10 scale? from what I understand in our current setup, I can loose 2 disks in total before i get data loss, one disk from each mirror?

 

How does this work with raid10 that have more than 4 disks? I can only find examples with 4 disks (guess it's easier to understand)

 

any help or info on this would be great.

 

thanks

Edited June 12, 2017 by Jaan

[sted]

isnt raid 10 only a 4 disk solution i diddnt think you could do it with more drives as its a mirrored span and iirc raid 0 dosent support more than 2 drives nore does raid 1

[JackCPickup]

isnt raid 10 only a 4 disk solution i diddnt think you could do it with more drives as its a mirrored span and iirc raid 0 dosent support more than 2 drives nore does raid 1

 

Minimum is 4, maximum depends on the controller.

[pcstru]

from what I understand in our current setup, I can loose 3 disks in total before i get data loss, One whole mirrored stripe and one disk from the oppsite mirror?

How many discs you can lose varies. In RAID 10 each disc is mirrored and then the mirrored pairs are joined into the final lump. So with 4 drives in the array and one down, there is a 1/3 chance that the next drive to fail will be the other one in that pair, which will be goodbye data. We have a RAID 10 with 24 drives; we could in theory lose 12 drives and still be OK, but we could also in theory lose only 2 drives and be stuffed.