An active-active Spectrum Scale cluster

In an active-active cluster, a single GPFS™ cluster contains two active sites and an optional tiebreaker site.

The high-level organization of an active/active GPFS cluster using hardware replication is illustrated in Figure 1.A single GPFS cluster is created over three sites. The data is mirrored between two active sites with a cluster configuration server residing at each site and a tiebreaker quorum node installed at the third location. The presence of an optional tiebreaker node allows the surviving site to satisfy the node quorum requirement with no additional intervention. Without the tiebreaker, the failover procedure requires an additional administrative command to relax node quorum and allow the remaining site to function independently. Furthermore, the nodes at the recovery site have direct disk paths to the primary site's storage.

The GPFS configuration resides either on the two configuration server (primary and secondary), when the cluster has been created with the Clustered Configuration Repository (CCR) disable option (mmcrcluster), or on each quorum node, when the cluster has Clustered Configuration Repository (CCR) enabled, or on the primary/secondary, when the Clustered Configuration Repository (CCR) is disabled.

Figure 1. A synchronous active-active replication-based mirrored GPFS configuration with a tiebreaker site
This figure illustrates a synchronous active-active replication-based mirrored GPFS configuration with a tiebreaker site. The entire figure represents one GPFS cluster. It consists of three sites, named: the GPFS production site, the GPFS recovery site, and the tiebreaker site. They are attached using an IP network. The GPFS production site has four nodes: one node designated as the primary cluster configuration server, two quorum nodes, and one non-quorum node. The GPFS production site has disks referred to as PPRC source volumes, and they are attached with shared NSD access. The GPFS recovery site has four nodes: one node designated as the secondary cluster configuration server, two quorum nodes, and one non-quorum node. The GPFS recovery site has disks referred to as PPRC target volumes, and they are attached with shared NSD access. The GPFS production site and the GPFS recovery site share their disks using shared NSD access. The Peer-to-Peer Remote Copy function also connects the disks from the GPFS production site and the GPFS recovery site. The tiebreaker site consists of one quorum node.
Parent topic: Synchronous mirroring utilizing storage based replication