HP StorageWorks XP Remote Web Console Software - Manual (Page 37)

TrueCopy for z/OS user guide 37
TrueCopy Volume Pair Status
TC390A displays the pair status for each volume in the selected logical CU image (CUI) of the connected
XP128/XP1024/XP10000/XP12000. The MCU maintains the status of the M-VOL and is responsible for
keeping the M-VOL and its R-VOL synchronized. The RCU maintains the status of the R-VOL. The MCU can
change the pair status of the M-VOL and R-VOL. The RCU can change the pair status of the R-VOL but not
the M-VOL. The MCU will detect when the RCU changes the R-VOL status (if the path status is normal) and
will change the M-VOL status accordingly. The TC390 pair status can be acquired from the MCU and RCU
using the TC390 software (Pair Status) and the CQUERY TSO command.
Table 9 on page 38 lists and describes the TC390 volume pair status descriptions. A volume that is not
assigned to a TC390 volume pair has the status simplex. When a TC390 pair is started, the MCU changes
the status of both volumes (M-VOL and R-VOL) to pending duplex. When the initial copy operation is
complete, the MCU changes the status of both volumes to duplex. When a pair is suspended from the
MCU, the MCU changes the status of the M-VOL and R-VOL (if the path status is normal) to suspended.
When a pair is suspended from the RCU, the RCU changes the status of the R-VOL to suspended, and the
MCU detects the pair suspension (if the path status is normal) and changes the M-VOL status to suspended.
When you delete a pair from the MCU, the MCU changes the status of the M-VOL and R-VOL (if the path
status is normal) to simplex. When you delete a pair from the RCU, the RCU changes the R-VOL status to
simplex, and the MCU detects the pair deletion (if the path status is normal) and changes the M-VOL status
to suspended.
TC390A-Specific Pair Status
The TC390A suspending and deleting transitional states occur when a request to change TC390A pair
status has been accepted, but the change to the requested status (suspended or simplex) is not yet
complete. These states are not reported to the host. In the case of suspending, both the user and the MCU
can request the status change. In the case of deleting, only the user can request the status change. If the
user requested the status change, the final status is reported at the end of the transition. If an error caused
the status to change to suspended, the suspended status is reported at the beginning of the transition.
The TC390A SEQCHK status is indicated when a TC390A pair assigned to a consistency group with the
System timer type accepts a non-time-stamped update from the primary system. The SEQCHK status does
not affect TC390A copy activities and will be removed when the next time-stamped update is successfully
copied to the R-VOL. However, if a disaster or system failure occurs before the next time-stamped update,
the update sequence consistency between the R-VOL and other R-VOLs in the consistency group is not
ensured. To ensure effective disaster recovery, you should detect and remove the source of the SEQCHK
status. The SEQCHK status can be caused by any of the following:
• An application may issue update I/Os bypassing the MVS standard I/O procedure.
• The I/O time-stamping function may not be active at the primary system.
Table 9 TrueCopy volume pair status
Pair Status Description
Simplex This volume is not currently assigned to a TC390 volume pair. When this volume is added
to a TC390 volume pair, its status will change to pending duplex.
Pending Duplex The TC390 initial copy operation for this volume pair is in progress. This volume pair is not
yet synchronized. When the initial copy is complete, the status changes to duplex.
Duplex This volume pair is synchronized. Updates to the M-VOL are duplicated on the R-VOL.