HP XP P9500 Storage - Manual (Page 11)

The following figure shows the data in track 2 is copied to the R-VOL and the data in track 3
becomes differential data because track 2 is used for I/O processing of the volume in the consistency
group when the split command is issued.
Figure 4 Splitting processing when split command is issued and there are some volumes in the
consistency group during the I/O processing (Cnt Ac-S Z volume)
Yet, while consistency isWhen I/O processing on a primary function ofpair in a group, certain
operations take priority. For example, if the PSUS command is issued to aconsistency group in(on
which one ofthe pairssplit command is in process) is required from the process of being
updated,server for open system or the host for mainframe system, if the splitting processing on the
corresponding pair ishas not PSUS immediately, as allcompleted, the other pairs are. Itsplitting
processing on the corresponding pair is PSUS only whengiven priority. After the updatepair has
been split, the I/O demand is accepted. If the suspending operation caused by a system failure
occurred to the pairs in a consistency group, the suspending operation is completed. This allows
forperformed similarly. Therefore, the data integrityconsistency of the pairs in the corresponding
group is maintained. At this time, the "IEA491E" message is displayed (logged) to be maintained
between P-VOLs and S-VOLs. The same behavior occursthe host for a suspend operation caused
bythe mainframe system failure.whenever the pair status changes to the pair suspended-error in
the case of Cnt Ac-S Z pairs. For more details of the message, refer to the HP P9000 Continuous
Access Synchronous for Mainframe Systems User Guide.
RAID Manager (RM) and Business Continuity Manager provide some options concerning the control
of access to P-VOL/M-VOL and S-VOL/R-VOL from the host after the pair is suspended. These
options can be specified when the pair is suspended. The following tables show whether or not
the host can access P-VOL/M-VOL or S-VOL/R-VOL when each option is specified.
An option must be selected in Business Continuity Manager although it is not necessary to select
an option in RAID Manager (RM). Moreover, any options cannot make Cnt Ac-S volume prohibit
Read access. For details of each option, see the HP P9000 RAID Manager User Guide,HP P9000
RAID Manager Reference Guide or the HP P9000 Business Continuity Manager User Guide.
Table 2 Whether or not the host can access P-VOL/M-VOL when each option is specified
Whether or not the host can access Option Operation
P-VOL/M-VOL
Cnt Ac-S Z volume Cnt Ac-S volume
Write Read Write Read
N Y N Y Write access to P-VOL/M-VOL is
prohibited. RAID Manager (RM)
Y Y Y Y No option for P-VOL/M-VOL is
selected.
Consistency groups 11