Continuous Access Xp Asynchronous Suspension Conditions - HP StorageWorks XP12000 User Manual

Continuous Access XP Asynchronous suspension conditions

Continuous Access XP Asynchronous operations involve additional suspension conditions related to
recordset operations. The MCU and RCU detect Continuous Access XP Async suspension conditions and
suspend Continuous Access XP Async pairs. When a Continuous Access XP Async pair is suspended,
cylinders containing the following records are marked in the cylinder bitmap as modified (to be copied
during the pairresync operation):
• Recordsets created by the MCU, but not yet sent to the RCU. After marking these P-VOL cylinders
as modified, the MCU discards these recordsets.
• Recordsets sent to the RCU, but not acknowledged by the RCU. The MCU marks these P-VOL
cylinders as modified and discards these recordsets, ensuring that recordsets lost during
transmission to the RCU are identified and marked.
• Recordsets that reached the RCU, but have not yet been settled. After marking these S-VOL
cylinders as modified, the RCU discards these recordsets.
• P-VOL records updated by host-requested write I/Os after the pair was suspended (same function
as for Continuous Access XP Synchronous pairs).
If a recordset is lost in transmission from the MCU to the RCU, the MCU's cylinder bitmap ensures
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 1 1 describes Continuous Access XP Asynchronous suspension conditions and indicates which CU
detects the condition and which pairs are suspended. The Continuous Access XP offloading timer option
(see Asynchronous copy
Group Option)) control Continuous Access XP Asynchronous suspension conditions. For more information
about Continuous Access XP Asynchronous suspension conditions, see the Troubleshooting chapter of
the HP StorageWorks Command View XP user guide for XP Disk Arrays or the HP StorageWorks XP
Remote Web Console user guide for the array.
Table 1 1 Continuous Access XP Asynchronous suspension conditions
Suspension condition
The MCU could not send a pending
recordset to the RCU before the offloading
timer async option expired.
During MCU power-on, the MCU could
not establish communications with the RCU
before the RCU ready timeout group option
expired.
The RCU could not settle a pending
recordset before the copy pending timeout
group option expired.
The RCU could not communicate with the
MCU before the copy pending timeout
group option expired (see
consistency group options (CT Group
Option)).
The RCU could not receive the recordset
successfully due to a hardware failure.
The RCU detected a logical error while
selecting the recordset to be settled.
The RCU could not settle the recordset due
to a hardware failure, track condition, or
logical error.
option) and timeout group options (see
Detected by
MCU
MCU
RCU
RCU
Modifying
RCU
RCU
RCU
Modifying consistency group options (CT
Continuous Access XP ASYNC pairs to
be suspended
All Continuous Access XP ASYNC pairs
with P-VOLs in the MCU.
All Continuous Access XP ASYNC pairs
with P-VOLs in the MCU.
All Continuous Access XP ASYNC S-VOLs
in the consistency group.
All Continuous Access XP ASYNC S-VOLs
in the consistency group.
Only the affected S-VOL.
All Continuous Access XP ASYNC S-VOLs in
the consistency group or only the affected
S-VOL, depending on type of failure and
error level Continuous Access XP ASYNC
pair option.
Continuous Access XP user guide
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