Settings - Hitachi VSP F1500 User And Reference Manual

TrueCopy/TrueCopy Async and Universal Replicator/global-active
device fence level settings
TrueCopy volume pairs are assigned a fence level for write I/Os to ensure
mirroring consistency of critical volumes. When the secondary volume takes
over from the primary volume, the takeover action is determined according to
the pair status and fence level of the corresponding secondary volume.
6-9 Relationship between TrueCopy pair statuses and fence levels on page
6-31 shows the relationship between TrueCopy pair statuses and fence levels.
The fence level for TrueCopy is Data, Status, Never. The fence level for
TrueCopy Async and Universal Replicator is always Async. The fence level for
global-active device is always Never.
• Mirror consistency = Identity and sequence of data is assured via error
notification after an I/O completion.
• Data consistency = Sequence of data is assured in I/O order based on
host.
6-30
Figure 6-11 TrueCopy Async suspension condition
Data replication operations with CCI
Command Control Interface User and Reference Guide
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