GPFS Server configurations
Several GPFS™ Server configurations are supported, which you can easily scale to fit the needs of your environment.
GPFS Primary configuration
A GPFS Primary configuration can support only one GPFS server. This primary server can have either a mirrored or a passive replica (but not both) attached for improved quality of service.
GPFS Mirrored configuration
A GPFS Mirrored configuration, consisting of a GPFS Mirror deployment and a GPFS Tiebreaker deployment, is an active replica of the GPFS Primary server deployment to which it is attached, and ensures a highly available file system for use by client applications. The GPFS Tiebreaker decides which GPFS configuration, Primary or Mirror, takes over the primary role of serving clients in the event that one or the other becomes unusable. The GPFS Mirror deployment is limited to a single GPFS server, to match its mirrored, Primary configuration. You can deploy the GPFS Mirror and GPFS Tiebreaker configurations on any systems with PureApplication® products installed (either PureApplication System or PureApplication Software) that have IP connectivity to the GPFS Primary deployment, but you should avoid significant network latency, which might affect file system performance.
If you have three systems with PureApplication products installed (either PureApplication System or PureApplication Software) in different data centers, or in different zones of a single data center, you should deploy these three GPFS Server configurations each in a separate system.
If you have two systems with PureApplication products installed, you can install an external GPFS Tiebreaker node on a separate system and attach that separate node to your GPFS cluster. For more information about setting up this external Tiebreaker node, see the links in the related concepts.
As an additional option with only two systems with PureApplication products installed, instead of installing an external GPFS Tiebreaker node, you can deploy a GPFS Tiebreaker configuration on the same system with either the Primary or Mirror configuration. For highest availability, assign each configuration to separate cloud groups which do not share compute nodes. With this setup, the Tiebreaker node does not reside on the same compute node as the Primary or Mirror node, and failure of any one compute node cannot bring down two GPFS instances at once.
As a further consideration, when locating the GPFS Tiebreaker configuration on the same system with either the Primary or Mirror configuration, if one system with PureApplication products installed is larger than the other, you might choose to locate the GPFS Primary and Tiebreaker configurations on your largest system, and the GPFS Mirror configuration on the smaller system.
Note also that the GPFS Tiebreaker configuration must have IP connectivity to both the Primary and Mirror configurations.
For more information about configuring an active/active GPFS deployment, see the links in the related tasks.
GPFS Passive replica configuration
A GPFS Passive configuration uses block storage replication in PureApplication System to act as a passive replica of the GPFS Primary server to which it is attached. This deployment is also limited to a single server to match the Primary configuration, and is useful in disaster recovery situations. Replication can occur in either synchronous or asynchronous modes, giving you more flexibility in locating your passive deployment thousands of kilometers from its primary configuration. For more information about block storage replication, as well as a general procedure for configuring an active/passive GPFS deployment, see the links in the related tasks.