S-Vol Write Option; Continuous Access Xp Asynchronous Recordset Operations - HP StorageWorks XP12000 User Manual

CAUTION:
You may specify the unit of Difference Management when you create a pair with the Paircreate
pane (see
XP1024/XP128, the unit of Difference Management is applied as it is when you specify the unit. If
XP12000 is connected with XP1024/XP128, the differential data is stored in units of cylinders. If
XP12000 is connected with XP1024/XP128 or XP1024/XP128, the maximum number of pairs that
you can create is the lesser number by comparing both numbers.
If XP12000 is connected with XP1024/XP128, you can use both the Remote Web Console software
and the Command Line Interface software to specify the unit of Difference Management: "Auto",
"Track", and "Cylinder". You can also refer to the setting of Difference Management by using them.
CAUTION:
If the unit of Difference Management is set to "Auto", "Track", or "Cylinder" will be set automatically
according to the number of cylinders of a volume that a pair will be created with. If CVS has been
used, the number of cylinders that you set with CVS software is applied. If the volume that you
want to create a pair with has 10,019 or more cylinders, "Cylinder" will be set. If the volume has
less than 10,019 cylinders, "Track" will be set.
NOTE:
If the unit of Difference Management is set to "Track" by using the Continuous Access XP software
from the Remote Web Console, the number of pairs that you can create with the array is restricted. If
the number of pairs that you create exceeds the restriction, the differential data will be stored in units
of cylinders automatically, and pairs will be created. To restrict automatic changing of the unit of
Difference Management, call the service engineer. If the unit of Difference Management is set to
"Track" by using the RAID Manager XP software, and if the number of pairs that you can create
exceeds the restriction, the differential data will not be stored automatically in units of cylinders,
and pairs will not be created.

S-VOL write option

Continuous Access XP provides an S-VOL write option that enables write access to the S-VOL of a split
Continuous Access XP pair. The S-VOL write option can be selected during the pairsplit-r operation and
applies only to the selected pairs. The S-VOL write option can be accessed only when you are connected
to the MCU. When you resync a split Continuous Access XP pair that has the S-VOL write option enabled,
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 ensures proper resynchronization of the pair.

Continuous Access XP Asynchronous recordset operations

Continuous Access XP Asynchronous recordsets contain P-VOL updates and associated control
information, including sequence number of the P-VOL update, which enables the RCU to maintain update
consistency of S-VOLs. Continuous Access XP Recordset operations include:
• Creating and storing recordsets at the MCU
• Sending recordsets to the RCU
• Storing recordsets at the RCU
• Selecting and settling recordsets at the RCU
• Types of recordsets
• Inflow control of recordsets
Creating Continuous Access XP volume pairs (Paircreate)). If XP12000 is connected with
Continuous Access XP user guide
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