Continuous Access Xp Suspend Types - HP StorageWorks XP12000 User Manual

When a Continuous Access XP Sync pair is suspended, the MCU stops performing update copy
operations to the S-VOL and may or may not continue accepting write I/Os for the P-VOL, depending
on the P-VOL fence level pair option. If a synchronous update copy operation fails, the MCU maintains
exact synchronization by reporting a unit check and decommitting the P-VOL update. The host system and
application program regard that write operation to the P-VOL as failed. If the MCU accepts write I/Os
for a suspended P-VOL, the MCU tracks P-VOL cylinders updated while the pair is suspended. When a
suspended sync pair is resumed, the MCU copies out-of-sync P-VOL cylinders to the S-VOL. Continuous
Access XP does not allow access to an S-VOL while the pair is suspended (only when split).
You must stop host I/Os before suspending Continuous Access XP Synchronous pairs with the Data
fence level and following conditions:
• Continuous Access XP Synchronous and Asynchronous pairs exist in the same disk array
• There are host I/Os to the Continuous Access XP Asynchronous pairs
If you do not stop host I/Os, pairs might be forcibly suspended because of a time-out error, and host
I/Os are rejected.
When a Continuous Access XP Asynchronous (Continuous Access XP Async) pair is suspended, the MCU
stops performing Continuous Access XP Async recordset operations for the pair. The MCU continues
accepting write I/Os for the suspended P-VOL and tracks P-VOL cylinders updated while the pair is
suspended. The MCU and RCU also tracks recordsets discarded during the pair suspension. When a
suspended Continuous Access XP Async pair is resumed, the RCU sends the S-VOL cylinder bitmap to the
MCU, and the MCU merges the P-VOL and S-VOL bitmaps to determine which cylinders are out-of-sync.
This method ensures that all cylinders containing recordsets discarded at the RCU are resynchronized
at this time.
A suspended (or split) Continuous Access XP Async S-VOL has an additional status called consistency
status. Consistency status is displayed only at the RCU and indicates the S-VOL's update sequence
consistency with respect to other S-VOLs in the same group. See
status for suspended/split Continuous Access XP Async S-VOLs.
Table 10 Continuous Access XP suspend types
Type
Applies to
P-VOL, S-VOL
PSUE, by RCU
P-VOL, S-VOL
PSUE, S-VOL Failure
PSUE, MCU IMPL P-VOL, S-VOL
P-VOL, S-VOL
PSUE, Initial Copy
Failed
S-VOL (Continuous
PSUE, MCU P/S
Access XP Async
OFF
only)
P-VOL, S-VOL
PSUS, Sidefile
overflow
(Continuous Access
XP Async only)
32
Continuous Access XP for the Array
Table 9
Description
The MCU detected an error condition at the RCU causing
the MCU to suspend the Continuous Access XP volume pair.
S-VOL suspend type is PSUE-S-VOL Failure.
The MCU detected an error during RCU communications or
update copy. In this case, S-VOL suspend type is usually
PSUE-S-VOL Failure. This suspend type is also used when the
number of paths falls below the minimum number of paths
setting on the RCU Option pane.
The MCU could not find valid control information in its
nonvolatile memory during IMPL. This condition occurs only
if the MCU is without power for more than 48 hours (power
failure and fully discharged backup batteries).
The Continuous Access XP pair was suspended before the
initial copy operation was complete. Data on the S-VOL is not
identical to data on the P-VOL.
The RCU received a request from the MCU to suspend the
S-VOL due to MCU power-off. The RCU stops expecting
recordsets from that MCU. The P-VOL status does not change
due to MCU power-off.
The amount of sidefile exceeds the specified "current pending
update data rate," and the RCU data is not transferred within
the specified "offloading timer."
for a description of consistency