HP StorageWorks XP Remote Web Console Software - Manual (Page 21)

operation. If the update copy operation fails, the RCU suspends either the affected pair or all
TrueCopy for Mainframe Asynchronous pairs in the consistency group, depending on the type
of failure. When the suspended TrueCopy for Mainframe Asynchronous pair or group is
resynchronized, the MCU and RCU negotiate the resynchronization of the pair(s).
The RCU does not allow a TrueCopy for Mainframe R-VOL to be online and rejects all host-requested
read and write I/O operations for a TrueCopy for Mainframe R-VOL. The TrueCopy for Mainframe
R-VOLs must be offline during normal TrueCopy for Mainframe operations.
TrueCopy for Mainframe provides a special R-VOL read option which allows read-only access to
the R-VOL while the pair is suspended. If you need write access to a TrueCopy for Mainframe
R-VOL, you must release the pair.
R-VOL Read Option
For additional flexibility, TrueCopy for Mainframe offers a special R-VOL read option. The HP
representative enables the R-VOL read option on the RCU (mode 20). The R-VOL read option allows
you to read a TrueCopy for Mainframe R-VOL only while the pair is suspended, that is, without
having to release the pair.
When you read a TrueCopy for Mainframe R-VOL from a host, the reference date in the VTOC is
updated. In this case, you must permit to update the VTOC.
The RCU will allow you to change only the VOLSER of the suspended R-VOL, so that the R-VOL can
be online to the same host as the M-VOL while the pair is suspended. All other write I/Os will be
rejected by the RCU. The MCU copies the M-VOL VOLSER back onto the R-VOL when the pair is
resynchronized.
If mode 20 and mode 190 are enabled simultaneously, the HP representative permits to only
update the VOLSER and VTOC of the TrueCopy for Mainframe R-VOL from a host while a pair is
suspended. The MCU copies the M-VOL VOLSER and VTOC back onto the R-VOL when the pair
is resynchronized.
When the R-VOL read option is not enabled and/or the pair is not suspended, the RCU rejects all
read and write I/Os to a TrueCopy for Mainframe R-VOL.
If you need write access to an R-VOL, you must release the pair.
For 2105 or 2107 controller emulation, the CSUSPEND command to the R-VOL of a suspended
TrueCopy for Mainframe pair will be rejected when the TrueCopy for Mainframe R-VOL read option
is used.
TrueCopy for Mainframe Async Recordset Operations
The TrueCopy for Mainframe Asynchronous recordsets contain the TrueCopy for Mainframe
Asynchronous M-VOL updates and the associated control information, including the time-stamp of
the M-VOL update, which enables the RCU to maintain update consistency of the TrueCopy for
Mainframe Asynchronous R-VOLs. TrueCopy for Mainframe Asynchronous recordset operations
include:
•
Creating and storing recordsets at the MCU
•
Sending recordsets to the RCU
•
Storing recordsets at the RCU
•
Selecting and settling recordsets at the RCU
•
Types of recordsets
•
Inflow control for sidefiles.
TrueCopy for Mainframe Async Recordset Operations 21