Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

TrueCopy for z/OS Usage Scenarios 7-11
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Analyzing the Consistency of TrueCopy for z/OS Async R-VOLs
Table 7-3 shows how to determine the consistency of a TCzA R-VOL based on
its pair status and consistency status. For TCzA R-VOLs with a consistency
status of Volume, the volume is not consistent with other volumes in the
same group, and further analysis will be required to determine the currency of
each of these R-VOLs. The currency of these R-VOLs can be determined by
using the sense information transferred via the ERC or by comparing the
contents of the R-VOL with other files which are confirmed to be current (e.g.,
DB2 log files). These R-VOLs should be recovered using the files which are
confirmed to be current.
Table 7-3 Analyzing the Consistency of TrueCopy for z/OS Async R-VOLs
Status of R-VOL
Usable for
Recovery? Description
Duplex
Pending Duplex
Simplex
No
No
No
These states do not usually occur during TCzA disaster recovery, because the
RCU suspends all TCzA pairs when communication with the MCU is lost. TCzA
R-VOLs in these states should not be used for disaster recovery.
Note: Simplex volumes cannot be distinguished from R-VOLs which have already
been released by the Delete Pair operation.
Suspended-Group Yes
The update sequence consistency across these R-VOLs is ensured at the point
in time indicated by the group consistency time. These R-VOLs can be used for
disaster recovery at the secondary system.
Note: Updates which were performed at the primary system after the indicated
consistency time were probably lost.
Suspended-Volume No
The contents of this R-VOL may be behind the other R-VOLs in the consistency
group. If this volume must be consistent with the other volumes in the same
group, this R-VOL should not be used for disaster recovery.
The cause for this status is:
– The TCzA Error Level pair option for this pair is Volume (not Group)
– This pair was suspended before the disaster/failure, at the beginning of the
rolling disaster, or during the initial copy operation.