gluster.md

Disperse volumes

To work correctly, we need to have a power of two available disks (>1). Plus you can't have 50% of redundancy. It "sounds" like a RAID5/6

It means there is a limited subset of possibilities, for example:

number of disks/bricks	redundancy	usable disks capacity
3	1	2
5	1	4
6	2	4
7	3	4
9	1	8
10	2	8
11	3	8
12	4	8
13	5	8
14	6	8
15	7	8

Replicated volumes

Here, it will use replicate (or replicate/distribute) with shards. Distribute will "pair" (for replication 2) bricks two by two, eg for 6 bricks: 1/2, 3/4, 5/6 will be mirrored. It sounds like a RAID10

number of disks/bricks	replication level	usable disks capacity
2	2	1
3	3	1
4	2	2
6	2	3
6	3	2
8	2	4
9	3	3
10	2	5
12	2	6
14	2	7
15	3	5
16	2	8