HP XP Continuous Access Software - Manual (Page 96)

96 Continuous Access XP for the XP1024/XP128
If power is removed from an RCU or remote copy connection while Continuous Access XP operations are
in progress, the MCU detects the communications failure, suspends all affected pairs, and generates SIMs
reporting the failures. The MCU changes the status of P-VOLs to suspended-by RCU, but cannot change
the status of S-VOLs.
If an MCU or RCU is powered off and its backup batteries are fully discharged while Continuous Access
XP pairs are suspended, the P-VOL and S-VOL cylinder maps are not retained. In this unlikely case, the
MCU and RCU mark all cylinders of all suspended Continuous Access XP volumes as modified, so the
MCU performs the equivalent of an entire initial copy operation when the pairs are resumed. (The S-VOL
cylinder map is used for Continuous Access XP Async operations and Continuous Access XP S-VOL write
enable option.)
Planned outage of MCUs
A planned MCU outage does not affect Continuous Access XP Synchronous. For Continuous Access XP
Asynchronous operations, the MCU must communicate with the RCU even when there are no P-VOL
update I/Os from the primary system. During the power-off sequence, the MCU automatically suspends
all Continuous Access XP Async pairs in the PAIR and COPY states (suspend type = MCU P/S-OFF).
During the power-on-reset sequence, the MCU automatically resumes these suspended pairs (pairs with
other suspend types are not automatically resumed).
Planned outage of RCUs or remote copy connections
You must split all affected Continuous Access XP pairs prior to a planned outage of an RCU or remote
copy connection component (for example, Fibre Channel switches). If you do not split the pairs first, the
MCU detects the communications failure, suspends all affected pairs, and generates SIMs reporting the
failures.
1. Identify all Continuous Access XP P-VOLs that will be affected by the equipment outage. You must
know the MCU, CU image, and ID (port, GID, LUN) for each P-VOL.
a. For an RCU power-off, identify all P-VOLs paired with S-VOLs in the RCU to be powered off.
b. For a remote copy connection outage, identify all P-VOLs in all MCUs using the path and
component to be powered off.
2. Connect to each MCU containing affected P-VOLs, and split all affected Continuous Access XP pairs.
Confirm that the pair status changes (Pair Operation tab or Pairdisplay pane).
3. Perform the planned outage of the RCU or remote copy connection.
4. When the RCU is fully powered on and ready to resume operations, resume (pairresync) all
Continuous Access XP pairs at each MCU. Confirm that the pair status changes.
Planned outage of MCUs and RCUs
When you plan an outage of Continuous Access XP MCUs and RCUs at the same time, MCUs must be
powered off before RCUs, and MCUs must be powered on after RCUs.
1. If RCU power-on will be difficult to control (for example, Power-Control-Interface setting), consider
increasing or disabling the RCU ready timeout group option (see ” Group options ” on page 24) for
each Continuous Access XP Async group with S-VOLs in RCUs to be powered off.
2. Perform the planned outage of MCUs (see ” Planned outage of MCUs ” on page 96). Do not power on
MCUs yet.
3. If an RCU to be powered off is connected to an MCU that is not powered off, split those Continuous
Access XP pairs before powering off the RCU.
4. Perform the planned outage of the RCUs (see ” Planned outage of RCUs or remote copy connections ”
on page 96).
5. Power on RCUs. Ensure that they are fully operational and ready to resume operations before
powering on MCUs.
6. Power on MCUs, and ensure that they are ready to resume operations. If you split any pairs in step 3 ,
resume (pairresync) those pairs now.