Copy sets

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During data replication, data is copied from a source volume to one or more target volumes, depending on the session type. The source volume and target volumes that contain copies of the same data are collectively referred to as a copy set.

Each volume in a copy set must be of the same size and volume type. For example, SAN Volume Controller volumes must be used with other SAN Volume Controller volumes. The number of volumes in the copy set and the role that each volume plays is determined by the session type that is associated with the session to which the copy set belongs.

The following table lists the estimated number of role pairs and volumes per copy set that are supported for each session type.

Table 1. Number of role pairs and volumes per copy set for each session type
Session	Role Pairs	Volumes
Basic HyperSwap	1	2
FlashCopy®	1	2
Snapshot¹	0	1
Metro Mirror Single Direction	1	2
Metro Mirror Failover/Failback	1	2
Metro Mirror Failover/Failback with Practice	3	3
Metro Mirror - Metro Mirror	3	3
Global Mirror Single Direction (IBM DS8000)	3	3
Global Mirror Single Direction (FlashSystems/IBM Spectrum® Virtualize, SAN Volume Controller)	1	2
Global Mirror Failover/Failback (IBM DS8000)	3	3
Global Mirror Failover/Failback (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	1
Global Mirror Failover/Failback with Practice (IBM DS8000)	5	4
Global Mirror Failover/Failback with Practice (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	3	3
Global Mirror Either Direction	5	4
Global Mirror Either Direction with Two-Site Practice	8	6
Global Mirror Failover/Failback with Change Volumes	1	4
Metro Global Mirror	6	4
Metro Global Mirror with Practice	8	5
Metro Mirror - Global Mirror	6	4
Metro Mirror - Global Mirror with Practice	9	5
Metro Mirror - Global Mirror with Site 3 Global Mirror	10	6
1. A FlashSystem/IBM Spectrum Accelerate Snapshot session requires that the user define only the H1 volumes. All target volumes are created on the same storage pool as the source volumes.

Table 2. Number of role pairs and volumes per copy set for each session type
Session	Role Pairs	Volumes
Basic HyperSwap	1	2
FlashCopy	1	2
Snapshot¹	0	1
Metro Mirror Single Direction	1	2
Metro Mirror Failover/Failback	1	2
Metro Mirror Failover/Failback with Practice	3	3
Metro Mirror - Metro Mirror	3	3
Global Mirror Single Direction (IBM DS8000)	3	3
Global Mirror Single Direction (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	2
Global Mirror Failover/Failback (IBM DS8000)	3	3
Global Mirror Failover/Failback (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	1
Global Mirror Failover/Failback with Practice (IBM DS8000)	5	4
Global Mirror Failover/Failback with Practice (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	3	3
Global Mirror Either Direction	5	4
Global Mirror Either Direction with Two-Site Practice	8	6
Global Mirror Failover/Failback with Change Volumes	1	4
Metro Global Mirror	6	4
Metro Global Mirror with Practice	8	5
Metro Mirror - Global Mirror²	6	4
Metro Mirror - Global Mirror with Practice	9	5
Metro Mirror - Global Mirror with Site 3 Global Mirror	10	6
Metro Mirror - Global Mirror with Site 4 Replication	11	6
Safeguarded Copy ³	1	2
1. A FlashSystem/IBM Spectrum Accelerate Snapshot session requires that the user define only the H1 volumes. All target volumes are created on the same storage pool as the source volumes. 2. For IBM FlashSystem® A9000 and A9000R storage systems, there are 3 role pairs, and 3 volumes. 3. Source volumes need to have the safeguarded capacity defined on the DS8000 for use in a Safeguarded Copy session.

Table 3. Number of role pairs and volumes per copy set for each session type
Session	Role Pairs	Volumes
Basic HyperSwap	1	2
FlashCopy	1	2
Snapshot¹	0	1
Metro Mirror Single Direction	1	2
Metro Mirror Failover/Failback	1	2
Metro Mirror Failover/Failback with Practice	3	3
Metro Mirror - Metro Mirror	3	3
Global Mirror Single Direction (IBM DS8000)	3	3
Global Mirror Single Direction (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	2
Global Mirror Failover/Failback (IBM DS8000)	3	3
Global Mirror Failover/Failback (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	1
Global Mirror Failover/Failback with Practice (IBM DS8000)	5	4
Global Mirror Failover/Failback with Practice (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	3	3
Global Mirror Either Direction	5	4
Global Mirror Either Direction with Two-Site Practice	8	6
Global Mirror Failover/Failback with Change Volumes	1	4
Metro Global Mirror	6	4
Metro Global Mirror with Practice	8	5
Metro Mirror - Global Mirror²	6	4
Metro Mirror - Global Mirror with Practice	9	5
Metro Mirror - Global Mirror with Site 3 Global Mirror	10	6
Metro Mirror - Global Mirror with Site 4 Replication	11	6
Metro Mirror - Metro Mirror with Site 4 Replication	5	4
Safeguarded Copy ³	1	2
1. A FlashSystem/IBM Spectrum Accelerate Snapshot session requires that the user define only the H1 volumes. All target volumes are created on the same storage pool as the source volumes. 2. For IBM FlashSystem A9000 and A9000R storage systems, there are 3 role pairs, and 3 volumes. 3. Source volumes need to have the safeguarded capacity defined on the DS8000 for use in a Safeguarded Copy session.

Table 4. Number of role pairs and volumes per copy set for each session type
Session	Role Pairs	Volumes
Basic HyperSwap	1	2
FlashCopy	1	2
Snapshot¹	0	1
Metro Mirror Single Direction	1	2
Metro Mirror Failover/Failback	1	2
Metro Mirror Failover/Failback with Practice	3	3
Metro Mirror Failover/Failback with Change Volumes	1	4
Metro Mirror - Metro Mirror	3	3
Global Mirror Single Direction (IBM DS8000)	3	3
Global Mirror Single Direction (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	2
Global Mirror Failover/Failback (IBM DS8000)	3	3
Global Mirror Failover/Failback (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	1
Global Mirror Failover/Failback with Practice (IBM DS8000)	5	4
Global Mirror Failover/Failback with Practice (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	3	3
Global Mirror Either Direction	5	4
Global Mirror Either Direction with Two-Site Practice	8	6
Global Mirror Failover/Failback with Change Volumes	1	4
Metro Global Mirror	6	4
Metro Global Mirror with Practice	8	5
Metro Mirror - Global Mirror²	6	4
Metro Mirror - Global Mirror with Practice	9	5
Metro Mirror - Global Mirror with Site 3 Global Mirror	10	6
Metro Mirror - Global Mirror with Site 4 Replication	11	6
Metro Mirror - Metro Mirror with Site 4 Replication	5	4
Safeguarded Copy ³	1	2
1. A FlashSystem/IBM Spectrum Accelerate Snapshot session requires that the user define only the H1 volumes. All target volumes are created on the same storage pool as the source volumes. 2. For IBM FlashSystem A9000 and A9000R storage systems, there are 3 role pairs, and 3 volumes. 3. Source volumes need to have the safeguarded capacity defined on the DS8000 for use in a Safeguarded Copy session.

Table 5. Number of role pairs and volumes per copy set for each session type
Session	Role Pairs	Volumes
Basic HyperSwap	1	2
FlashCopy	1	2
Snapshot¹	0	1
Metro Mirror Single Direction	1	2
Metro Mirror Failover/Failback	1	2
Metro Mirror Failover/Failback with Practice	3	3
Metro Mirror Failover/Failback with Change Volumes	1	4
Metro Mirror - Metro Mirror	3	3
Global Mirror Single Direction (IBM DS8000)	3	3
Global Mirror Single Direction (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	2
Global Mirror Failover/Failback (IBM DS8000)	3	3
Global Mirror Failover/Failback (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	1	1
Global Mirror Failover/Failback with Practice (IBM DS8000)	5	4
Global Mirror Failover/Failback with Practice (FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller)	3	3
Global Mirror Either Direction	5	4
Global Mirror Either Direction with Two-Site Practice	8	6
Global Mirror Failover/Failback with Change Volumes	1	4
Metro Global Mirror	6	4
Metro Global Mirror with Practice	8	5
Metro Mirror - Global Mirror²	6	4
Metro Mirror - Global Mirror with Practice	9	5
Metro Mirror - Global Mirror with Site 3 Global Mirror	10	6
Metro Mirror - Global Mirror with Site 4 Replication	11	6
Metro Mirror - Metro Mirror with Site 4 Replication	5	4
Safeguarded Copy ³	1	2
Migration	1	2
1. A FlashSystem/IBM Spectrum Accelerate Snapshot session requires that the user define only the H1 volumes. All target volumes are created on the same storage pool as the source volumes. 2. For IBM FlashSystem A9000 and A9000R storage systems, there are 3 role pairs, and 3 volumes. 3. Source volumes need to have the safeguarded capacity defined on the DS8000 for use in a Safeguarded Copy session.

Use the Add Copy Sets wizard to add copy sets to a session. You can select a storage system; a logical subsystem (LSS), I/O group, or pool; or a single volume for reach role and then create one or more copy sets for the session.

You can use one of the following volume pairing options to automatically create multiple copy sets in the same session.

Storage system matching (IBM® DS8000® Metro Mirror sessions only): Creates copy sets by matching volumes (based on the volume IDs) across all LSSs for the selected storage systems. For example, volume 01 on the source LSS is matched with volume 01 on the target LSS.
You can select the storage system and select All Logical Subsystems in the list of LSSs. You can also do auto-matching at the LSS level for Metro Mirror sessions.
LSS, I/O group, or pool matching: Creates copy sets by matching all volumes based on the selected LSS, I/O group, or pool for each role in copy set.
Select the storage system and LSS, I/O group, or pool, and then select All Volumes in the Volume list.

If you do not want to use the auto-generated volume pairing for a copy set, clear that copy set so that it is not added during the wizard. Then, add the remaining copy sets and reopen the Add Copy Set wizard and manually enter the volume pairings that you want.

Invalid copy set are not added to the session. Copy sets can be invalid if their volumes are not the same type or size.

You can remove copy sets that you do not want to add to the session, even if they are valid. You can use this process to filter and eliminate unwanted copy sets before they are added to the session.

You can export the copy sets to take a snapshot of your session at a particular point in time for backup purposes.

Note: You can copy an entire storage system only for Metro Mirror sessions.

Adding copy sets

When you create a copy set for a session, a warning is displayed if one or more of the selected volumes exist in another session. If the volume you selected is in another session, confirm whether you want to add the volume to this session. Ensure that you intend to have the volume in multiple sessions because having the volume in multiple sessions can create conflicts. A scenario in which you would want the same volumes in multiple sessions is one in which you create a session for normal replication, and then create another session for a disaster recovery practice. You must use the same target volumes in both sessions.

You can use extent space-efficient volumes as copy set volumes, depending on the capabilities of the storage system.

Removing copy sets

You remove a copy set or range of copy sets by selecting the following items:

Source volume
LSS, I/O group, or pool
Storage system

When the list of copy sets that meet your criteria is displayed, you can select the copy sets that you want to remove.

The consequence of removing copy sets varies depending on the state of the session:

Defined: There is no relationship on the hardware. The copy set is removed from the Copy Services Manager data store.
Preparing or Prepared: The copy set is copying data, so Copy Services Manager terminates the hardware relationship for the copy set. The rest of the copy sets continue to run uninterrupted.
Suspended or Target Available: Any existing relationships on the hardware are removed for the copy set.

Before you remove all copy sets from that session, terminate the session. Removing the copy sets when the session is active can considerably increase the amount of time it takes for the copy set removal to complete. Copy sets are removed one at a time, and when the session is active, commands are issued to the hardware. However, if you terminate the session first, then commands are not issued to the hardware and the removal process completes faster.

Tip: When you a remove copy set from Copy Services Manager, you might want to keep hardware relationships on the storage systems. These relationships are useful when you want to migrate from one session type to another, or when you are resolving problems. For more information about keeping the hardware relationships when you are removing copy sets, see Removing Copy Sets.

Depending on the storage system, the following actions occur when a copy set is removed:

DS8000:

The complete copy set is removed from Copy Services Manager.
Any Peer-to-Peer Remote Copy (PPRC) pair that is part of a Global Mirror consistency group is removed from the consistency group on the storage system.
If the PPRC pair is part of a Global Mirror consistency group and is the last remaining source volume in a subordinate session, the subordinate session is removed from the storage system.
If the PPRC pair is the last remaining participant in a Global Mirror session, the Global Mirror session is removed from the storage system.
Any PPRC relationship remains on the storage system.
FlashCopy relationship remains on the storage system if the hardware background copy is not complete.

FlashSystems/IBM Spectrum Virtualize, SAN Volume Controller, or a FlashSystem/IBM Spectrum Accelerate

The complete copy set is removed from Copy Services Manager.
FlashCopy, Metro Mirror, and Global Mirror relationships are pulled out of their consistency group. If they are the last remaining relationship in a consistency group, that consistency group is removed from the hardware.

When you specify the force removal option, all knowledge of the specified copy set is removed from Copy Services Manager, even if the relationship itself still exists. In this situation, you are not able to remove the relationship by using Copy Services Manager because no information about the relationship exists. If you force a removal of a copy set and the removal fails, you must manually remove the relationship from the hardware. If you do not, you cannot to create new relationships.

One benefit of forcing a removal of the copy sets is that Copy Services Manager does not manage the consistency of copy sets that it has no knowledge of. This situation means that more commands to the session do not affect the removed copy sets, even though they are still in a relationship on the hardware.

If you do not specify the force removal option and an error occurs that prevents the hardware relationships from being removed, the copy set is not removed from Copy Services Manager. The copy set remains as part of the session, and you can still perform actions on it.