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.

Figure 1. PPRC volume states
There are several possible PPRC volume states. They are described in detail later in this topic.

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.