The system
layer affects how the system interacts with another system and other external systems that
run IBM® Storage Virtualize
software.
Systems that run IBM Storage Virtualize software can either be
in the replication layer or the storage layer.
Differences between the storage layer and the replication layer
This table compares the characteristics and requirements of storage layer and replication layer
systems.
Table 1. Comparison of storage layer and replication layer systems
Storage layer
Replication layer
The system can complete replicate with other storage-layer systems.
The system can provide external storage for replication-layer systems.
The system cannot use another Storwize® family or FlashSystem family system that
is configured with storage-layer as external storage.
The system can complete replicate with other replication-layer systems.
The system cannot provide external storage for other IBM Storage Virtualize systems.
The system can use another Storwize family or FlashSystem family system that
is configured with storage-layer as external storage.
A FlashSystem family
system is in the replication layer by default, but the layer can be changed. For example, you might
want to change a system to a replication layer to replicate with another system in the storage
layer. Systems in a Flash Grid must be in the replication layer.
To create a partnership between systems, both systems must be in the same layer. Figure 1. Example configuration with systems in different layers
Changing the layer of a FlashSystem family
system
To change the storage layer of an existing system with internal storage before you add a second
system into the SAN zone, you do not need to stop I/O operations.
However, if the system has Fibre Channel (FC) connections to another FlashSystem family, or system in the SAN
fabric, I/O operations must be stopped temporarily. In this scenario, the FC ports must be disabled
(for example, by unplugging all the FC ports, changing zoning, disabling switch ports) before you
change the system layer. Then, you must re-enable the FC ports.
Before you change the system layer, the following conditions must be met:
No host object can be configured with worldwide port names (WWPNs) from other IBM Storage Virtualize systems.
No system partnerships can be defined.
No IBM Storage Virtualize systems can
be visible on the SAN fabric.
To change the layer of a system, follow these general steps:
Use the lssystem command to check
the current system layer.
Configure SAN zoning so that the system whose layer you are changing is not
visible to any other system.
Ensure that all other configuration requirements are met.
Run the detectmdisk command to
ensure that the system detects any fabric changes that were done in step 3.
Enter the one of the following commands to switch the system to the appropriate layer.
