HP StorageWorks XP Remote Web Console Software - Manual (Page 33)

Hitachi TrueCopy for z/OS user guide 33
NOTE: If there is a network problem, lack of bandwidth, or lack of sufficient Fibre links, the sidefile will
grow and the microcode will add delay to host I/O until the sidefile goes below a certain level again.
Disabling this function will cause the pairs to suspend.
SIM reporting for TC390A sidefile conditions is enabled only when SVP system option mode 118 or 464 is
ON (see Table 3 on page 18). The reported SIMs when SVP system option mode 118 or 464 is ON,
however, do not support a CLPR. When this SIM is reported to the host, the SIM reference code is indicated
as 490x-yy (“x” is CU number, and “yy” is LDEV number). For more information about the SIM reference
code, call your HP Account Support Representative.
You can disable the command retry delay for a limited number of critical volumes using the special “No
delay” parameter for the CESTPAIR TSO command (see ” CESTPAIR ” on page 165). When this parameter
is set, the XP12000/XP10000 will not delay host write I/Os to the M-VOL until the TC390A sidefile amount
reaches the puncture threshold (threshold + 10%). This prevents performance degradation for critical
volumes and should be used only for a small number of volumes.
Figure 5 Graduated delay process for sidefile management
TrueCopy Asynchronous consistency group operations
TC390A consistency groups enable update sequence consistency to be maintained across a group of
volumes. The R-VOLs of the pairs in a consistency group must be located within one RCU (n-to-1
requirement). The TC390A consistency group operations include the following:
• Group options
• Group consistency time
• Group operations
Only TCzA pairs that belong to the same CLPR can be allocated to one consistency group.
Group options
TC390A provides the following options for each consistency group: Timer Type, Time Out [Copy Pending],
and Time Out [RCU Ready]. These options are selected when you add a group. To change the timeout
options of a group, you must suspend all pairs in the group first. To change the timer type option, you must
delete all pairs. The Timer Type and Time Out [Copy Pending] options must be the same for all MCUs that
contain M-VOLs in the group. The Time Out [RCU Ready] option can be different at each MCU if necessary.