An IBM® Storwize® family system
is in one of two layers: the replication layer or the storage
layer.
The system layer affects how the system interacts with
and external Storwize family systems.
Differences between the storage layer and the replication
layer
In storage layer, a
Storwize family
system has the following characteristics and requirements:
- The system can
complete Metro
Mirror and Global Mirror replication with other
storage-layer systems.
- The system can provide
external storage for replication-layer systems or SAN Volume Controller.
- The system cannot use another Storwize family system that is configured with
storage-layer as external storage.
In replication layer, a
Storwize family
system has the following characteristics and requirements:
- The system can
complete Metro
Mirror and Global Mirror replication with other
replication-layer systems or SAN Volume Controller.
- The system cannot
provide external storage for a replication-layer system or SAN Volume Controller.
- The system can use another Storwize family system that is configured with storage-layer as external storage.
A Storwize family system is in the storage layer
by default, but the layer can be changed. For example, you might want to change a Storwize V7000 system to a replication layer if
you want to use it to complete Global Mirror or Metro
Mirror with a SAN Volume Controller system.
Changing the layer of a Storwize family system
Before you change the system layer, the following conditions must be met:
- No host object can be configured with worldwide port names (WWPNs) from a Storwize family system.
- No system partnerships can be defined.
- No Storwize family system can be
visible on the SAN fabric.
The layer can be changed during normal host I/O.
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 chsystem -layer
replication to switch to the replication layer or chsystem -layer storage to switch to the
storage layer.
- If the SAN configuration was changed in step 2,
restore the normal SAN configuration.
- Run the detectmdisk command to update the list of MDisks.