Recovery group management

A recovery group is a collection of servers and pdisks.

Scale-out recovery groups have from 4 to 32 identically equipped servers, and each server contributes the same number and type of pdisks to the recovery group.

Shared recovery groups have two servers, and each server simultaneously accesses all of the pdisks in the enclosure twin-tailed between the two servers.

Paired recovery groups have two servers, one primary and one backup, and each recovery group of a pair owns half of the pdisks from the enclosures twin-tailed between the two servers.

In any recovery group, pdisks of the same size and hardware type are collected into declustered arrays. In this context, declustered array means a user declustered array, which is a declustered array where vdisk sets may be defined and where vdisk NSDs are created. Paired recovery groups also have log-only declustered arrays that only contain log tip vdisks and can never contain vdisk sets and vdisk NSDs.

For information on adding disks in the declustered array of the recovery group, see the topic Adding new disks in the declustered array of the recovery group in the IBM Storage Scale Erasure Code Edition Guide.