Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

3-12 Preparing for TrueCopy for z/OS Operations
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Caution: The bitmap areas that are used for TC-MF are shared with
Universal Replicator for z/OS. If you use both TC-MF and Universal
Replicator for z/OS, use the total value of both pairs. Also, if you use the
same volume with TC-MF and Universal Replicator for z/OS, use the total
value of both pairs regardless of whether the volume is P-VOL or S-VOL.
• The unit of Difference Management (track or cylinder):
The differential data between P-VOL and S-VOL is stored in units of tracks
or cylinders.
Caution: You may specify the unit of Difference Management when you
create a pair with the Add Pair dialog box. If USP V is connected with
TagmaStore USP/NSC or Lightning 9900V, the unit of Difference
Management is applied as it is when you specify the unit. If USP V is
connected with TagmaStore USP/NSC or Lightning 9900V, the maximum
number of pairs that you can create is the lesser number by comparing
both numbers.
If USP V is connected with TagmaStore USP/NSC or Lightning 9900V, you
can use both the Storage Navigator software and the Command Control
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 VLL has been used, the
number of cylinders that you set with VLL 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
TrueCopy for z/OS software from the Storage Navigator computer, the number
of pairs that you can create with the storage system 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.