HP StorageWorks XP Remote Web Console Software - Manual (Page 36)

Table 12 Suspend Types (PSUE) (continued)
Description Applies to Type
The RCU received a request from the MCU to suspend the
S-VOL due to an MCU power-off. The RCU suspended all
S-VOLs of the corresponding pairs. The P-VOL status does not
change due to an MCU power-off. S-VOL
(XP Continuous
Access
Asynchronous only)
MCU P/S OFF
1. The amount of the sidefile exceeds the specified current
pending update data rate, and the RCU data is not
transferred within the specified offloading timer.
2. In case the system option mode 549 is ON, the suspend
occurred due to the RIO completion waiting TOV. The
suspend type is Sidefile Overflow.
P-VOL, S-VOL Sidefile overflow
(XP Continuous
Access
Asynchronous only)
XP Continuous Access Asynchronous Suspension Conditions
XP Continuous Access Asynchronous operations involve additional suspension conditions related
to recordset operations. Both the MCU and RCU can detect XP Continuous Access Asynchronous
suspension conditions and suspend XP Continuous Access Asynchronous pairs. The MCU stores
the differential data per XP Continuous Access Asynchronous P-VOL to the shared memory. The
RCU stores the differential data per XP Continuous Access Asynchronous S-VOL to the shared
memory. When an XP Continuous Access Asynchronous pair is suspended, the tracks that contain
the following records are marked in the differential data as modified (to be copied during the
pairresync operation):
•
The recordsets that were created by the MCU, but not yet sent to the RCU. After marking these
P-VOL tracks as modified, the MCU discards these recordsets.
•
The recordsets that were sent to the RCU, but not acknowledged by the RCU. The MCU marks
these P-VOL tracks as modified and discards these recordsets. This ensures that recordsets lost
during transmission to the RCU are identified and marked.
•
The recordsets that reached the RCU, but have not yet been settled. After marking these S-VOL
tracks as modified, the RCU discards these recordsets.
•
The P-VOL records updated by host-requested write I/Os after the pair was suspended (same
function as for XP Continuous Access Synchronous pairs).
If a recordset is lost in transmission from the MCU to the RCU, the MCU’s differential data ensures
that the missing recordset is marked. After the MCU sends the recordset to the RCU, the MCU does
not remove the sidefile entry for the recordset from its cache until it receives an I/O completion
signal (device end) from the RCU.
Table 13 (page 36) describes XP Continuous Access Asynchronous suspension conditions and
indicates which CU detects the condition and which pairs are suspended. The XP Continuous
Access offloading timer option and timeout group options (see
“Changing the Consistency Group
Options” (page 106) ) are used to control the XP Continuous Access Asynchronous suspension
conditions. See “Resolving XP Continuous Access Asynchronous Suspension Conditions” (page 160)
for troubleshooting information for XP Continuous Access Asynchronous suspension conditions.
Table 13 XP Continuous Access Asynchronous Suspension Conditions
XP Continuous Access Asynchronous
Pairs to be Suspended Detected by: Suspension Condition
All XP Continuous Access Asynchronous
pairs with P-VOLs in the MCU. MCU The MCU could not send a pending recordset to the RCU
before the offloading timer async option expired.
All XP Continuous Access Asynchronous
pairs with P-VOLs in the MCU. MCU During an MCU power-on, the MCU could not establish
communications with the RCU before the Time Out (RCU
Ready) group option expired.
36 About XP Continuous Access Operations