Initial copy parameters, Continuous access xp initial copy, And pair options of the paircreate pane – HP XP Continuous Access Software User Manual
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Continuous Access XP for the XP1024/XP128
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Type: Synchronous or Asynchronous of the pair created.
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Mode: Entire: Copy all cylinders. No Copy: Do not copy.
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Fence: Conditions under which the MCU rejects write operations to the P-VOL: Never, Data, or Status.
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Pace: Number of tracks (1-15) for initial copy.
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Priority: Priority (scheduling order) of initial copy operations.
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Diff: In the measurement of the Cylinder or the Track, Continuous Access XP manages differentials
among data.
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CTG: Consistency group used for pair created (Asynchronous pairs only).
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ErrLvl: Error level, Group or LU. When a failure occurs, pairs in the same group or in an LU are
suspended (Asynchronous pairs only).
Continuous Access XP initial copy and pair options of the Paircreate pane
Continuous Access XP initial copy and pair options specify the fence level, initial copy parameters, and
asynchronous parameters. Initial copy and pair options are selected on the Paircreate pane. While the
initial copy operation is in progress, the initial copy options cannot be changed unless you delete
(pairsplit-S) and then restart (paircreate) the pair. After the initial copy operation is complete, you can only
change Continuous Access XP pair options (Fence Level and Error Level).
Fence Level (Continuous Access XP Synchronous only)
Fence Level: Conditions under which the MCU rejects write operations to the P-VOL, which is known as
“fencing.” This option is very important for disaster recovery planning (see ”
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Never: The P-VOL is never fenced. If the Continuous Access XP volume pair is split or suspended, write
operations to the P-VOL are accepted.
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Data: The P-VOL is fenced when the MCU cannot successfully execute an update copy operation for
any reason.
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Status: The P-VOL is fenced only if the MCU cannot change the S-VOL status to suspended when an
update copy operation fails. If the MCU changes the S-VOL status to suspended, subsequent write
operations to the P-VOL are accepted, and the MCU tracks all P-VOL updates while the pair is
suspended.
Initial Copy parameters
Initial Copy: Initial copy mode for new pairs. The default is Entire Volume.
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Entire Volume: The initial copy operation copies all cylinders on the P-VOL (except diagnostic and
unassigned alternate tracks) to the S-VOL.
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No Copy: The initial copy operation is not performed. The MCU performs update copy operations as
needed.
CAUTION:
Ensure that the P-VOL and S-VOL are already identical when using this setting.
Initial Copy Pace: Maximum number of tracks (1-15) that can be copied at one time by the Continuous
Access XP initial copy operation before the MCU accepts another host request for that P-VOL. A high
setting (for example, 15 tracks) speeds up the initial copy operation, but may affect the disk array’s I/O
performance if the P-VOL experiences high write I/O activity. A lower setting (for example, 3 tracks)
slows down the initial copy operation to minimize impact on the disk array’s I/O performance.
Priority: Order in which initial copy operations are performed if the number of requested initial copy
operations is greater than the maximum initial copy activity setting on the RCU Option pane (see
” on page 56). The highest priority is 1, and the lowest priority is 256
(current default = 32). Use the Continuous Access XP initial copy priority option to spread initial copy
operations across disk array groups and disk array domains (ACP pairs) to reduce initial copy time and
host I/O contention.