1–14
Performing CCI Operations
Hitachi AMS 2000 Family Command Control Interface (CCI) Reference Guide
Splitting pairs (pairslpit)
The pairsplit command stops updates to the secondary volume of a pair
(see
). The pairsplit command allows read/write access to the
secondary volume. The pairsplit command can be applied to a paired logical
volume or to a group of paired volumes.
lists and describes the
pairsplit command parameters and returned values.
•
Figure 1-6: Pair Splitting
The pairsplit command allows read/write access to the secondary volume,
depending on the selected options (-r, -rw, -S, -R, -E, -ms, -mscas, -RB).
The primary volume’s host is automatically detected by the pairsplit
command, so the host does not need to be specified in the pairsplit
command parameters. If the –S option (simplex) is used, the volume pair
is deleted, the volumes are returned to the simplex state, and the primary
and secondary volume status is lost. Paired volumes are split as soon as the
pairsplit command is issued. If you want to synchronize the volumes, the
pairsplit command must be issued after write I/Os to the paired volume
have been completed.
When splitting a pair, regardless of whether you can change the pair status
of S-VOL, changing the pair status of P-VOL to SMPL takes priority.
Therefore, if the pair status of S-VOL cannot be changed to SMPL, the pair
status of P-VOL might not correspond with that of S-VOL.
When a path failure has occurred or when S-VOL is not used temporarily (for
example, while formatting), the pair status of S-VOL cannot be changed to
SMPL.
When you want to change the status of P-VOL and S-VOL to SMPL, a
pairdisplay command is issued and a pairsplit –R command is issued for S-
VOL that is not SMPL. (This can be specified for TrueCopy and TCE).
When the pairsplit –R is issued for S-VOL in paired state, a pairsplit –S is
issued for P-VOL to change the status of P-VOL to SMPL.
When the S-VOL of the TCE pair is placed in the SMPL status through an
issue of a command for the pair splitting (pairsplit –R) to the TCE pair, the
S-VOL data may become unsettled data that is being copied. Therefore, to
use the data as the settled one on which the P-VOL data has been reflected,
Summary of Contents for AMS 2000 Series
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