z/VM: CP Commands and Utilities Reference - z/VM - IBM

Responses
Attention: Some guests, MVS for example, require that both the primary and
the secondary be attached.
22. The primary device of the duplex pair can be a free volume only when the
secondary device of the duplex pair is a free volume.
23. When a duplex pair has been established by CP, the guest will not be allowed
to fail the primary if permanent errors occur on volid-defined minidisks. The
recovery action will have to be done manually with the DUPLEX command.
24. The primary and secondary volumes should be on different DASD strings. This
provides greater data availability than duplex pairs on the same DASD string.
25. This command may produce delayed responses.
Response 1:
Response 1 has three types of responses. When establishing or re-establishing a
duplex pair, one or more of the following response types will occur:
v Immediate Response
v Delayed Response
v Response to System Operator
Immediate Response: If a duplex pair is established or re-established immediately,
this response will be displayed:
Duplex pair (prdev,srdev) - active
where:
prdev
is the real device number of the primary volume in the duplex pair.
srdev
is the real device number of the secondary volume in the duplex pair.
Delayed Response: If synchronization of the contents of the two volumes is in
progress, this response will be displayed:
Command started:
DUPLEX prdev ON srdev {COPY } PACE nnn [SECVolid volid]
{RESYNCH}
where:
prdev
is the real device number of the primary volume in the duplex pair.
srdev
is the real device number of the secondary volume in the duplex pair.
nnn
is the copy pace value.
volid
is the volume identification label for the former secondary volume after DUPLEX
ON is issued to replace the secondary volume of an existing duplex pair.
When the duplex pair is established or re-established, the following response will be
displayed.
Duplex pair (prdev,srdev) - active
DUPLEX
Chapter 2. CP Commands 417