HP StorageWorks XP24000 Continuous Access Software User and Reference Guide, v01 (T5278-96002, June 2007)

P-VOL of Pair
Priority
LUN 03
1
The MCU will star
t
the initial copy operations for LUNs 003, 005, 000,
and 004 immediat
ely; then start LUN 001 when one of the first four initial
LUN 05
2
copy operation
siscomplete; andthenstart LUN002 when thenextinitial
copy operation
is
complete. If more Continuous Access pairs are created,
LUN 00 3
the MCU also pr
ioritizes the initial copy operations by the time requested,
so that all pai
rs
in the first group are started before any pair in the next
LUN 04 4
group is start
ed.
LUN 01, 02
5
Note: If the time out error occurs during the Paircreate o p eration, the c opy operation may n ot be
executed correctly in the order that you have set with the Priority parameter. Thetimeout error
maybecausedbythe CU configu ration or a remote copy path error. Review the error, release
the
pair with the error, and then retry the Paircreate operation.
Pair Options
When you create new Continuous Access pairs, you select the pair options on the Paircreate dialog box
(see “Creating Continuous Access Pairs” on pa ge 105) . You can change the fence level and error level
pair options after a pair has been added (see “Changing Pair Options” on page 110). You cannot
change the difference mana gement or CT g roup of an existing pair. You need to release and then
restart the pair to change these options.
P-VOL Fence Level (Synchronous only): Specifies the conditions under which the MCU will
reject wri
te operations to the P-VOL, which is known as fencing: never, data, or status
(default
=
Never). This parameter is ver y important for disaster recovery planning (see
“Considering the P-VOL Fence Level Setting” on page 127).
• Never: The P-VOL will never be fenced. If the Continuous Access pair is split or suspended,
write ope
rations to the P-VOL will be accepted. (The fence level for all Continuous Access
Asynchronous pairs is Never.)
• Data: The P-VOL will be fenced when the MCU cannot successfully execute an update copy
operati
on
for any reason.
• Status: The P-VOL will be fenced only if the MCU is not able to change the S-VOL status to
suspended when a n update copy operation fails. If the MCU changes the S-VOL status to
suspended, subsequent write operations to the P-VOL will be accepted, and the MCU will keep
track o
f
all P-VOL updates while the pair is suspended.
CT Group (Asynchronous only): Specifies the consistency group number for new pairs. All Continuous
Access As ynchronous pairs must be assigned to a consistency group. To change the consistency group to
which a
pair
is assigned, you must release and then restart the pair with the desired group selected.
Error
level (Asynchronous only) (default = Group):
• Group: When the specified pair is suspended, all pairs in the same group will be suspended,
even if the failure affects only that pair and not the entire group.
Important : Select the Group error level for all pairs which are essential to disaster recovery.
Suspended Continuous Access A synchronous S-VOLs with the LU error level should not be used
for d
isaster recovery.
• LU: If the failure affects only the specified pair, then only that pair will be suspended. A failure
that affects an entire group will always result in the suspension of all pairs in the g roup, as well as
all other affected Continuous Access pairs.
Changing Pair Options
The Change Pair O ption dialog box (see Figure 48 on page 111) allows you to change the pair options
(fence level, error level) for existing Continuous Access pairs. To open the Change Pair Option dialog
box, click the Pair Operation tab, select a CU g rouping, CU, port, or host group from the tree, select
P-VOL from the list, right-click, and click the Change Pair Option command.
110
Performing Continuous Access Pair Operations