Identifying Peer-to-Peer Remote Copy volume states
In order to manage peer-to-peer remote copy (PPRC) operations, you need to know the state of PPRC volumes. Figure 1 shows the different volume states possible with PPRC. There are additional states, SUSPEND.PM and SUSPEND.CG, not included in the illustration.
To determine the state of a volume, issue the CQUERY command to that volume. Querying PPRC volumes describes an example of the command and the returned result.
The possible states for a volume are:
- SIMPLEX
- PENDING
- PENDING.XD
- DUPLEX
- SUSPENDED
- SUSP(n).XD
- SUSPEND.CG
- SUSPEND.PM
- MTIR
- PENDING.FC
- UNKNOWN
The states that apply to volumes in cascading PPRC relationships are identified as follows:
- SIMPLEX.CAS
- PNDING.CAS
- PNDING.X.C
- DUPLEX.CAS
- SUSP.CAS
- SUSP(n).CAS
- SUS(n).X.C
The following definitions apply to volume states:
- SIMPLEX
- The initial state of a volume.
- PENDING
- The initial state of a defined volume pair. This state can also occur after a storage subsystem failure when PPRC reestablishes the volume pair. PPRC is in the process of copying data from the primary volume to the secondary volume.
- PENDING.FC
- This state indicates that the PPRC pair has gone pending due to a FlashCopy operation.
- PENDING.XD
- The state of a volume pair established in PPRC extended distance while the copy operation is in process.
- DUPLEX
- The state of a volume pair after PPRC has completed the copy operation, and the volume pair is in synchronization.
- MTIR
- The state of a volume in a Multi-Target
Internal Relationship (MTIR pair). This is an internal relationship that is created between two
multi-target secondary volumes when the Multi-Target Mirror
environment is established (when multiple secondaries are created using the PPRC establish command).
It is also known as the Multi-Target Incremental Resync relationship.
If multi-target PPRC is disabled in PARMLIB, the state is UNKNOWN rather than MTIR.
- Cascading States
- The state of two volume pairs established through another application (for example, ICKDSF or ESS Specialist) such that the secondary of one pair is the primary of another pair.
- SUSPENDED
- The state of a volume pair when the storage subsystems cannot keep the primary and secondary volumes synchronized, or when either the primary host or recovery site host issues a CSUSPEND command. A PPRC volume pair will go into suspended state, for instance, when the primary system storage control fails to complete a write operation to the recovery system storage control. During this suspended state, the primary volume’s storage control records the cylinders that applications update. When you issue a CESTPAIR command with the RESYNC parameter, PPRC must only recopy data in the cylinders that have changes. Both volumes return to a synchronized state.
- SUSP(n). XD
- The state of a volume pair established in PPRC extended distance and in suspended state.
- SUSPEND.CG
- The PPRC pair was suspended as a result of a request to pause the Global Mirror session with consistency.
- SUSPEND.PM
- The state of a volume pair when a FlashCopy® Establish with Preserve Mirror Required was requested and the inband FlashCopy Establish sent from the local control unit failed, resulting in the Local B to Remote B PPRC pair being suspended. Local B and Remote B are FlashCopy targets. For more information, see Preserving mirroring.
- UNKNOWN
- The state of a volume in a Multi-Target Internal Relationship (MTIR pair) if multi-target PPRC is disabled in PARMLIB, or the CQUERY is issued with UNFORMAT parameter.