Cluster Export Services overview

Cluster Export Services (CES) includes support for monitoring high availability through protocols and commands.

High availability

With GPFS™, you can configure a subset of nodes in the cluster to provide a highly available solution for exporting GPFS file systems by using the Network File System (NFS), Server Message Block (SMB), and Object protocols. The participating nodes are designated as Cluster Export Services (CES) nodes or protocol nodes. The set of CES nodes is frequently referred to as the CES cluster.

A set of IP addresses, the CES address pool, is defined and distributed among the CES nodes. As nodes enter and leave the GPFS cluster, the addresses in the pool can be redistributed among the CES nodes to provide high availability. Remote clients can use these addresses to access the cluster.

Monitoring

Each CES node runs a separate GPFS utility that monitors the state of the node. This utility includes checks of the CES addresses that are assigned to the node and a check of the processes that implement the enabled services in the CES cluster. Upon failure detection, the monitoring utility might mark the node as temporarily unable to participate in the CES cluster and reassign any addresses that are assigned to the node.

Protocol support

CES supports three export protocols: NFS, SMB, and Object. Each protocol can be enabled or disabled in the cluster. If a protocol is enabled in the CES cluster, all CES nodes run servers for that protocol.

Protocols are enabled and disabled with the mmces command:

mmces service enable nfs: Enables the NFS protocol in the CES cluster.
mmces service disable obj: Disables the Object protocol in the CES cluster.

Commands

To set or configure CES options, the following commands are used:

mmces: Sets the CES address pool and other CES cluster configuration options.
mmnfs: Sets the NFS configuration operations.
mmobj: Sets the Object configuration operations.
mmsmb: Sets the SMB configuration operations.
mmuserauth: Configures the authentication methods that are used by the protocols.

For more information, see mmces command, mmnfs command, mmobj command, mmsmb command, and mmuserauth command.

Restrictions

For an up-to-date list of supported operating systems, specific distributions, and other dependencies for CES, refer to the IBM Spectrum Scale™ FAQ in IBM® Knowledge Center.

If the SMB protocol is enabled, the CES cluster is limited to 16 nodes that must be of the same architecture.

Each CES node must be able to host all addresses in the CES address pool.

Each CES node must have network adapters capable of supporting all IP addresses in the CES address pool. The primary address of these adapters should not be used as a CES address.