Consistency groups
A consistency group is a copy group recognized by a storage system.
A consistency group updates the S-VOLs in the same order that data was put onto the P-VOLs. The
data on an S-VOL is guaranteed to be identical to the data on a P-VOL at consistency times.
Therefore, data at the secondary site can be used to recover the data at the primary site. This is
called preserving consistency. The consistency of updates is assured throughout the entire consistency
group. Table 1 (page 23) lists the methods for preserving consistency for each copy type.
Table 1 Methods to preserve consistency for each copy type
Consistency preservation methodConsistency group ID
specification method
Consistency group IDCopy type
The NORMAL ATTIME Suspend
function or the CAJ ATTIME
Consistency group IDs are
specified in the Copy Group
OptionalBusiness Copy for
Mainframe
Suspend function can be used toAttributes panel in which the
preserve the consistency of copy
groups.
copy group attributes are
defined for the consistency
group ID already registered in
the storage system by Remote
Web Console.
The Cnt-Ac S Z consistency
preservation function in Business
When working with Cnt-Ac S
Z, you don't need to register
OptionalContinuous
Access
Continuity Manager can be usedthe consistency group ID in theSynchronous for
Mainframe to preserve consistency. Forstorage system. Consistency
details about how to implementgroup IDs are specified in the
this, see “The Continuous AccessCopy Group Attributes panel
Synchronous Consistency
Preservation Function” (page 78).
in which the copy group
attributes are defined for the
When the Open/MF Consistency
Preservation Function is used,
consistency group ID for Cnt-Ac
S Z.
consistency is only preserved for
the Cnt-Ac S Z copy group in the
storage system that contains the
combined consistency group. For
details on the Open/MF
Consistency Preservation
Function, see “Open/MF
Consistency Groups” (page 25).
Consistency is preserved by using
only the Continuous Access
Consistency group IDs are
specified in the Copy Group
YesContinuous
Access
Asynchronous for MainframeAttributes panel in which theAsynchronous for
Mainframe functions of the storage system. Ifcopy group attributes are
the ATTIME suspend function isdefined for the consistency
used, Continuous Accessgroup ID already registered in
Asynchronous for Mainframethe storage system by Remote
Web Console. copy groups that are configured
across multiple storage systems
can be suspended at the same
time.
Consistency is preserved by using
only the Cnt Ac-J Z functions of
The journal group number
already registered in the
YesNon-4x4
configurations
Continuous
Access Journal
for Mainframe the storage system. If the CAJstorage system by the Remote
ATTIME suspend function is usedWeb Console is specified as
for BC Z copy groups that linkthe consistency group ID. In
with Cnt Ac-J Z copy groups, BCBusiness Continuity Manager,
Z copy groups that arethe journal group number for
configured across multiplethe primary site is used as the
storage systems can be
suspended at the same time.
consistency group ID, and the
journal group number for the
secondary site is used as the
sub consistency group ID. The
Grouping to simplify volume operations 23
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