RAIN

ECC Layout Types

EOS supports five types of RAIN layouts:

name	redundancy	algorithm	description
raid5	N+1	single parity raid	can lose 1 disk without data loss
raiddp	4+2	dual parity raid	can lose 2 disks without data loss
raid6	N+2	Erasure Code (Jerasure library)	can lose 2 disks without data loss
archive	N+3	Erasure Code (Jerasure library)	can lose 3 disks without data loss
qrain	N+4	Erasure Code (Jerasure library)	can lose 4 disks without data loss

The layout is set in a namespace tree via eos attr -r set default=<name> <tree>.

The minimum number of stripes is currently 6 for all erasure coding layouts (raiddp, raid6, archive, qrain).

The default layout can be defined using default space policies. See Space and Application Policies.