Hitachi TAGMASTORE MK-90RD011-25 - Manual (Page 186)

168 Chapter 4 Performing CCI Operations
4.2 Creating Pairs (Paircreate)
WARNING: Use the paircreate command with caution. The paircreate command starts the
Hitachi TrueCopy/ShadowImage initial copy operation, which overwrites all data on the
secondary/target volume. If the primary and secondary volumes are not identified correctly,
or if the wrong options are specified (e.g., vl instead of vr), data will be transferred in the
wrong direction.
The paircreate command generates a new volume pair from two unpaired volumes. The
paircreate command can create either a paired logical volume or a group of paired volumes.
The paircreate command allows you to specify the direction (local or remote) of the pair
generation (see Figure 4.1). If local (vl option) is specified, the server issuing the paircreate
command has the primary volume. If remote (vr option) is specified, the remote server has
the primary volume. The -split option of the paircreate command (ShadowImage only) allows
you to simultaneously create and split pairs using a single CCI command. When -split is used,
the pair status changes from COPY to PSUS (instead of PAIR) when the initial copy operation
is complete. Table 4.3 lists and describes the paircreate command parameters and returned
values. Table 4.4 lists and describes the error codes for the paircreate command.
Note: Snapshot support for the TagmaStore USP/NSC depends on the microcode version.
Pair
generation
command
Server A Server B
Local is specified.
(Remote is specified.)
Primary
volume
(Secondary
volume)
Secondary
volume
(Primary
volume)
Paired logical volumes
Entire copy
Figure 4.1 Pair Creation
Before issuing the paircreate command, make sure that the secondary volume is not
mounted on any system. If the secondary volume is found to be mounted after paircreate,
delete the pair (pairsplit -S), unmount the secondary volume, and then reissue the
paircreate command.
Note: The paircreate command terminates before the initial copy operation is complete
(except when the nocopy option is specified). Use the pair event waiting or pair display
command to verify that the initial copy operation completed successfully (status changes
from COPY to PAIR, or from COPY to PSUS if the -split option was specified). The execution
log file also shows completion of the initial copy operation.
Hitachi TrueCopy only: The paircreate command cannot execute copy rejection in case of
an error condition which made the target volume is accompanied by maintenance work.