Upgrading AFM and AFM DR

Consider the following while you upgrade Active File Management (AFM) or Active File Management - DR (AFM DR).

Before you upgrade to a newer version of IBM Storage Scale, consider the version from which you are upgrading. IBM Storage Scale supports a limited form of compatibility with an earlier version between two adjacent releases and hence, coexistence and compatibility measures are required. For more information, see IBM Storage Scale supported upgrade paths. The limited compatibility with an earlier version allows temporarily operating with some IBM Storage Scale nodes that are running on the newer version, and some nodes that are running an earlier version. Within a cluster, because of this you can perform an online upgrade to the new IBM Storage Scale version, if upgrade from your current version to the newer version is supported.

In AFM and multi-cluster environment, individual clusters can be upgraded at different schedules. The access to the file system data can be preserved even though some of the clusters might still be running on an earlier version. Home or the cache cluster must be upgraded independent of the other.

During an offline upgrade, the IBM Storage Scale service is interrupted. For an offline upgrade, you must shut down the cluster and suspend the application workload of the cluster. During an online upgrade, IBM Storage Scale service is not interrupted. In an online upgrade, the system is upgraded node-by-node or failure group-by-failure group. During the upgrade, IBM Storage Scale runs on a subset of nodes. You can also perform offline upgrades, if you can shut down the entire cluster. An offline upgrade is similar to the online upgrade procedure. As the entire cluster is offline, it is possible to upgrade to the latest code level instead of upgrading to an intermediate level, as might be needed during an online upgrade.

Before you start an AFM upgrade, the home cluster or primary cluster for AFM-DR must be upgraded first before the cache or secondary cluster.

Before you consider an online upgrade of the home or cache, ensure that:
  • The cluster is healthy and operational.
  • IBM Storage Scale is running on all nodes that are defined in the cluster.
  • All protocols that are defined on the protocol node are running.
  • Ensure that the storage at the cache cluster is adequate by using mmrepquota command during the home upgrade. Specifically, check the storage when the cache eviction feature is enabled for the storage management.

Cache cluster - In multiple gateway environment, gateway nodes can be upgraded one by one. In these cases, filesets, which are associated with the gateway node to upgrade, are transferred to another gateway node, and any write-class operation triggers the recovery feature. This recovery feature builds the queue on the associated gateway node to continue processing the operations to home. Thus, cache to home are not disconnected. However, some performance degradation can be seen due to another gateway node that is working for the connect for those filesets that are hosted on the upgrade node previously. In heavy load systems, transferring the filesets to another gateway node might have a performance impact. It is advised to choose a time for such upgrades where the load on the system or the number of data transfers is minimal.

Parallel data transfers enabled with GW mappings - in multiple-gateways environment, where parallel data transfer is enabled with multiple gateways, upgrading any of these mapped nodes results in a normal data transfer path.
Note: Fileset mapping might remain intact after an upgrade, depending on the afmHashing version that is being used.

When gateway nodes manage many filesets, it is recommended to perform the rolling upgrade by using start stop replication. For more information about the start and stop replication, see Using stop and start replication to upgrade AFM and AFM DR.

If you want the replication to continue as-is during the upgrade, you can tune the number of parallel recoveries that are run on a gateway node by using the afmMaxParallelRecoveries parameter. The number of filesets that are specified as the afmMaxParallelRecoveries value are accessed for recovery. After recoveries are complete on these specified filesets, other filesets are accessed for recovery. By default, the afmMaxParallelRecoveries parameter is set to 0, and the recovery process is run on all filesets. You can restrict the number of recoveries by specifying the afmMaxParallelRecoveries value. The restriction on recoveries conserves hardware resources.

Home cluster - Cluster Export Services (CES) provides highly available file and object services to an IBM Storage Scale cluster by using Network File System (NFS), Object, or Server Message Block (SMB) protocols. With the CES environment, the exports at home can be seen from cache by using the CES IP addresses. These IP addresses can align to protocol nodes when the CES node that already holds the CES IP address is shut down for an upgrade. The IP addresses alignment is according to the CES IP address distribution policies. Cache might see a short disruption at the time of CES failover at home but cache filesets continue to operate.

In a non-CES or NFS Server at Home environments, home to cache disconnects until the upgrade of NFS home server is complete. In a disconnected mode, the cache builds up the queue for application operations. After Home is available, these operations are pushed to Home.
Note: Shut down the NFS server before you issue the mmshutdown command on home nodes. When the IBM Storage Scale system upgrade is complete and the node mounts the file system, you can start the NFS server.
Note: The mmclone command is not supported on cache for AFM and primary for AFM DR. Clones that are created at home or secondary are replicated as different files. While you upgrade to IBM Storage Scale 4.2.2 or later, the cache cluster must be upgraded before you consider upgrading the home cluster.

The cache cluster and the home cluster can be upgraded by using the same method. If any of these clusters has protocol nodes, upgrade these nodes. For more information, see Online upgrade support for protocols and performance monitoring.

After you completed upgrade, see Completing the upgrade to a new level of IBM Storage Scale. To know upgrade support for protocols and performance monitoring, see Online upgrade support for protocols and performance monitoring.