Rcu Option Pane - HP StorageWorks XP12000 User Manual

Figure 31 RCU Option pane
Use the RCU Option pane to set the options for the RCU.
• Minimum Paths: Minimum number of paths required for each RCU connected to the current MCU.
The default is one. If you specify a number that is larger than the number of paths set on the
Register RCU pane or the number of paths falls below this number (for example, failed path), an
error occurs. When errors occur, the MCU suspends all affected Continuous Access XP (and any
mainframe) pairs to prevent remote copy operations from adversely affecting performance due to
the inadequate number of paths. If the MCU contains Continuous Access XP pairs, which contain
critical data for disaster recovery, set minimum number of paths to one, so Continuous Access XP
operations continue even if there is only one path to an RCU. If you need high performance at
the MCU, set minimum number of paths to two or more (up to eight per CU image), depending
on number of pairs managed by the MCU.
CAUTION:
If Continuous Access XP volume pairs are suspended because number of paths dropped below
this setting, the P-VOL fence-level pair option (see
(Paircreate)) determines whether Continuous Access XP Synchronous P-VOLs are fenced (that is, all
write operations are rejected).
• RIO MIH Time: Time value for the remote I/O (RIO) missing interrupt handler (MIH), which is
the wait time until data transfer from the MCU to RCU is complete. The RIO MIH time must be
from 10 to 100 seconds. The default is 15 seconds. This setting is available for both serial and
Fibre Channel interfaces.
• Round Trip Time (ms): Used for initial copy operations. This setting give a priority to a remote
I/O for an update copy operation.
• Cancel button: Cancels the registering RCU operation.
• Set button: Sets the registering RCU operation with the option set on the RCU Option pane.
The Round Trip Time setting is used for initial copy operations. This setting gives priority to remote I/Os
for update copy operations.
When an initial copy operation is in progress, the copy pace is automatically adjusted based on the
actual time required for initial copy, which can be obtained by subtracting the specified Round Trip Time
(obtained using the formula below) from the remote I/O response time. If the actual time required for
the initial copy operation is large, the update copy workload is relatively high. Therefore, the copy
pace of the initial copy is slowed. When the time is relatively small, the copy pace speeds up to the
specified value. In this way, the influence of the exclusive line use in the initial copy operation on the
host performance is curbed.
NOTE:
This option is available only for Continuous Access XP Sync pairs. For Continuous Access XP Aync pairs,
this option value is invalid.
The default value of Round Trip Time is 1 ms. You can specify 1 ms to 500 ms. Use the following
formula to calculate the Round Trip Time:
76
Continuous Access XP for the Array
Creating Continuous Access XP volume pairs