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Redundancy configurations in a partition mobility environment

In some situations, you can move a logical partition to a destination system that provides less redundancy than the source system.

The mobile partition can access its physical storage through redundant paths on the source system. The redundant paths can include redundant Virtual I/O Server (VIOS) logical partitions, VIOS logical partitions with redundant physical adapters, or both. In most cases, successful partition mobility requires that you maintain the same level of redundancy on the destination system as on the source system. Maintaining redundancy requires that you configure the same number of VIOS logical partitions with the same number of physical adapters on the source and destination servers.

In some situations, however, you might need to move a logical partition to a destination system with less redundancy than the source system. In these situations, you receive an error message explaining that the redundant configuration on the source system cannot be maintained on the destination system. Before you move the mobile partition, you can respond to the error in one of the following ways:

You can change the configuration on the destination system so that you maintain redundancy.
You can override virtual storage errors when possible. In other words, you can accept the reduced level of redundancy and continue with partition mobility.

The following table explains the configurations in which you can move a logical partition to a destination system with less redundancy than the source system. Some of these situations result in one or more failed paths to the physical storage after the mobile partition moves to the destination system.

Table 1. Redundancy options for partition mobility
Redundancy change	Source system	Destination system
Redundant paths to the physical storage are maintained. However, the paths go through separate VIOS partitions on the source system and go through the same VIOS partition on the destination system.	The source system has two VIOS partitions. One physical Fibre Channel adapter in each VIOS partition provides the mobile partition with redundant paths to its physical storage.	The destination system has two VIOS partitions. Two physical Fibre Channel adapters in the VIOS partition provide the mobile partition with redundant paths to its physical storage.
Redundant paths to the physical storage are not maintained, and redundant VIOS partitions are not maintained. The mobile partition accesses its physical storage through redundant paths on the source system and through one path on the destination system.	The source system has two VIOS partitions. One physical adapter in each VIOS partition provides the mobile partition with redundant paths to its physical storage. (The physical and virtual adapters can be SCSI or Fibre Channel adapters.)	The destination system has one VIOS partition. One physical adapter in the VIOS partition provides the mobile partition with one path to its physical storage. (The physical and virtual adapters can be SCSI or Fibre Channel adapters.) This situation results in one successful path and one failed path to the physical storage. In an attempt to maintain redundancy, partition mobility creates two sets of virtual adapters. It maps one set of virtual adapters to the physical adapter, but it cannot map the other set of virtual adapters. The unmapped connections become a failed path. The paths consist of the following mappings. The adapters are either all SCSI adapters or all Fibre Channel adapters: The path to the physical storage consists of the following mappings: A virtual client adapter to a virtual server adapter. The virtual server adapter to the physical adapter. The physical adapter to the physical storage. The failed path consists of a virtual client adapter that is mapped to a virtual server adapter.
Redundant paths to the physical storage are not maintained. The mobile partition accesses its physical storage through redundant paths on the source system and through one path on the destination system.	The source system has one VIOS partition. Two physical Fibre Channel adapters in the VIOS partition provide the mobile partition with redundant paths to its physical storage.	The destination system has one VIOS partition. One physical Fibre Channel adapter in the VIOS partition provides the mobile partition with one path to its physical storage. This situation results in one successful path and one failed path to the physical storage. In an attempt to maintain redundancy, partition mobility creates two sets of virtual adapters. It maps one set of virtual adapters to the physical adapter, but it cannot map the other set of virtual adapters. The unmapped connections become a failed path.

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Last updated: Sat, March 17, 2018