You can change the copy type of both relationships and consistency groups
between Metro Mirror and Global Mirror.
The system supports the following
types of relationships and consistency groups:
- Active-active (for HyperSwap® volumes)
- Metro Mirror
- Global Mirror without change volumes (cycling mode set to None)
- Global Mirror with change volumes (cycling mode set to Multiple)
If necessary, you can change
the copy type of a Metro Mirror or Global Mirror remote-copy relationship or consistency group without re-creating
the relationship or consistency group with the different type. For
example, if the latency of the long-distance link affects host performance,
you can change the copy type to Global Mirror to improve host performance
over high latency links. For Global Mirror relationships with multiple cycling mode, changes are tracked
and copied to intermediate change volumes. The changes are transmitted
to the secondary site periodically to lower bandwidth requirements.
If you are changing either a Metro Mirror or Global Mirror relationship
or consistency group to a Global Mirror with change volumes (cycling
mode set to Multiple), you must create change volumes on both the
master and auxiliary volumes that are used in the relationship or
consistency group. Note: You cannot change the type
of an active-active relationship or consistency group.
Before you change the copy type of either a relationship or consistency group, consider the
following requirements:
- Any relationship or consistency group must be in the stopped state (Inconsistent Stopped,
Consistent Stopped, or Idling state).
- When you change the type for a consistency group, all relationships within the group also
change their copy type.
You can change the copy type by using either the management GUI or the command-line interface.
Using the management GUI
In the management GUI, complete these steps:
- To change a single relationship, complete these steps:
- In the management GUI, select .
- Expand Not in a group and right-click the relationship that you want to
change and select Edit Relationship.
- In the Edit Relationship dialog, select either Metro or
Global for the new copy type. If you are changing the copy type from a Metro to a Global copy type,
you need to specify whether to use cycling mode. Set the value to None if
you do not want change volumes that are created for this relationship. Set the value to
Multiple to create change volumes for this relationship. With multiple
cycling mode, changes are tracked and copied to intermediate change volumes and are transferred to
the secondary volume periodically to reduce bandwidth requirements. If you select
Multiple for the cycling mode, you can specify the number of seconds between
copy cycles for the relationship.
- Click OK.
- If you are updating a consistency group, complete these steps:
- In the management GUI, select .
- Right-click the consistency group and select Edit Consistency Group.
- In the Edit Consistency Group dialog, select either Metro
or Global for the new copy type. If you are changing the copy type from a Metro to a Global copy
type, you need to specify whether to use cycling mode. Set the value to None
if you do not want change volumes that are created for this relationship. Set the value to
Multiple to create change volumes for this relationship. With multiple
cycling mode, changes are tracked and copied to intermediate change volumes and are transferred to
the secondary volume periodically to reduce bandwidth requirements. If you select
Multiple for the cycling mode, you can specify the number of seconds between
copy cycles for the consistency group. The new copy type and settings apply to all the relationships
within the group.
- Click OK.
- If you are changing a relationship or a consistency group that either had existing change
volumes or are changing to a Global Mirror with change volumes, make change on both the master and
auxiliary systems, by completing these steps:
- On the master system, select in the management GUI, right-click the relationship or consistency group that you
changed and select Global Mirror Change Volumes. You can select one of the
following options:
- Create New
- Select this option if you are changing the copy type from either a Metro Mirror or Global Mirror
relationship or consistency group to a Global Mirror with change volumes.
- Add Existing
- Select this option if existing change volumes exist on the system.
- Delete
- Select this option if you are changing the copy type from a Global Mirror with change volumes to
either a Global Mirror without change volumes or a Metro Mirror relationship or consistency
group.
- On the auxiliary system, select in the management GUI, right-click the relationship or consistency group that you
changed and select Global Mirror Change Volumes. You can select one of the
following options:
- Create New
- Select this option if you are changing the copy type from either a Metro Mirror or Global Mirror
relationship or consistency group to a Global Mirror with change volumes.
- Add Existing
- Select this option if existing change volumes exist on the system.
- Delete
- Select this option if you are changing the copy type from a Global Mirror with change volumes to
either a Global Mirror without change volumes or a Metro Mirror relationship or consistency
group.
Using the CLI
To change the copy type of a relationship, enter one of the following commands:
To change the copy type of a consistency group, enter one of the following commands:
- If you are changing a Metro Mirror consistency group to a Global Mirror consistency group
without cycling mode, enter this
command:
chrcconsistgrp -global-cyclingmode nonerc_consist_group_name
where
rc_consist_group_name is the name of the consistency group that you are
changing. All new settings apply to all the relationships within the group.
- If you are changing a Metro Mirror consistency group to a Global Mirror consistency group with
multiple cycling mode, enter this
command:
chrcconsistgrp -global-cyclingmode multi-cycleperiodseconds periodrc_consist_group_name
where
period is the number of seconds that a cycling mode is completed for the
relationship and rc_consist_group_name is the name of the consistency group
that you are changing. All new settings apply to all the relationships within the group.
- If you are changing a Global Mirror consistency group to a Metro Mirror consistency group, enter
this
command:
chrcconsistgrp -metrorc_consist_group_name
where
rc_consist_group_name is the name of the consistency group that you are
changing. All new settings apply to all the relationships within the group.