HP XP Continuous Access Software - Manual (Page 71)

Continuous Access XP user guide for the XP1024/XP128 71
array. Async options apply to the entire physical control unit, including all Continuous Access XP P-VOLs
and S-VOLs behind the control unit.
Figure 43 Async Option pane
All default settings indicate the current settings.
• Pending Update Data Rate (%): Continuous Access XP Asynchronous sidefile threshold, which is
maximum amount of cache that can be used for storing Continuous Access XP Async recordsets
(sidefiles). Select any value between 30% and 70% (10% increments) (see ” Inflow control of
recordsets ” on page 22).
The current pending update data rate is common to both Continuous Access XP and TC390
operations. The most recently entered value is applied to all Continuous Access XP Async operations.
If one or more consistency groups exist, this setting cannot be changed. This setting can only be
changed when no CT groups are assigned.
You can specify the Pending Update Data Rate from the Async Option pane of TC390. If the specified
Pending Update Data Rate is less than the I/O Delay Start or I/O Delay Increase specified from the
Async Option pane of Continuous Access XP, the Pending Update Data Rate is available.
• Offloading Timer (sec.): Amount of time (0-255 seconds) the MCU waits to send a Continuous Access
XP Async recordset to the RCU. The MCU suspends all affected Continuous Access XP Async volume
pairs if it cannot offload a recordset to the RCU within the specified time (for example, the RCU is still
responding channel-command-retry).
The offloading timer should be set to less than the HBA I/O timeout value.
When channel-extenders are used for Continuous Access XP Async, the offloading timer should be set
to 35 seconds or less to avoid affecting host I/O performance.
NOTE: The following are available in firmware version 21.07.04 or later (XP1024/XP128).
• I/O Delay Start: Threshold (0-70%), which is maximum amount of cache for starting inflow control for
the asynchronous copy. When amount of cache used for async recordsets reaches the specified
threshold, the MCU controls the cache inflow.
• I/O Delay Increase: Threshold (0-70%), which is maximum amount of cache for starting to strengthen
control over inflow for the asynchronous copy. When amount of cache used for async recordsets
reaches the specified threshold, the MCU controls cache inflow.