HP StorageWorks XP Remote Web Console Software - Manual (Page 22)

When I/O processing on a pair in a consistency group (on which the split command is in process)
is required from the server, if the splitting processing on the corresponding pair has not finished,
the splitting processing on the corresponding pair is given priority. After the pair has been split,
the I/O demand is accepted.
CAUTION: When I/O is required from the server during the split command is in process and if
the microprocessor that has the port connected to the corresponding host path is blocked, the data
consistency of the corresponding consistency group will not be ensured. If the blockade has
occurred, resynchronize the corresponding consistency group and perform the split command
again.
XP Continuous Access Asynchronous consistency group operations
XP Continuous Access Asynchronous consistency groups maintain update sequence consistency
across an aggregated data set spanning a group of volumes. P-VOLs and S-VOLs of the pairs in
a consistency group must be located within one physical MCU and one physical RCU (1-to-1
requirement). XP Continuous Access consistency group operations include:
•
“Group options” (page 22)
•
“Group operations” (page 23)
Group options
XP Continuous Access provides the following options for each consistency group: copy pending
timeout and RCU ready timeout. These options are selected when you add a group, and can be
modified only when the group does not contain any P-VOLs in the MCU.
Copy pending timeout
This group option specifies maximum delay allowed for XP Continuous Access Async copy
operations. The RCU suspends all S-VOLs in the group when:
•
The RCU has not had any communications from the MCU within the specified time. This
situation might indicate a disaster or failure at the primary site.
•
The RCU has received recordsets from the MCUs but has not been able to settle a particular
recordset within the specified time. This situation might indicate the RCU does not have enough
resources to handle remote copy and I/O workloads.
RCU ready timeout
This group option specifies maximum delay allowed for re-establishing MCU-RCU communications
following MCU power-off. During MCU power-on, the MCU re-establishes communications with
all registered RCUs. If the MCU cannot re-establish communications with an RCU within the specified
time, the MCU suspends all affected XP Continuous Access Asynchronous volume pairs.
22 Overview of XP Continuous Access operations