Hitachi TrueCopy for z/OS (T1711-96009, June 2006)
TrueCopy for z/OS user guide 47
• TC390 option(s) enabled on the XP1024/XP128/XP12000/XP10000 and on the Command View XP
management station or XP Remote Web Console (see ”Installing the TrueCopy Software” on page 54).
Requirements and Restrictions
TC390 has the following requirements and restrictions:
• Track format
• One-to-one volume copy operations
• Duplicate VOLSER (Volume Serial Number)
• Logical volume image (LVI) (also called device emulation or device type)
• Accessing TC390 M-VOLs and R-VOLs
• Cache, NVS, and DASD fast write
• Consistency groups
Track Format
TC390 has the following disk track format requirements that the user must follow. TC390 cannot detect
exceptions to these requirements. The MCU will abort the TC390 initial copy operation if the track format
for both the M-VOL and R-VOL does not meet the following requirements:
• The TC390 M-VOL and R-VOL must have the same track format.
• Record zero (R0) must be standard format, with key length of zero and data length of eight. The MCU
will abort the initial copy operation if R0 is not standard format.
• The CCHH (logical cylinder address and logical head address) of R0 must be identical to the physical
cylinder address and physical head address of the track.
• The CCHH of each user record in a track must be unique.
One-to-One Volume Copy Operations
TC390 requires a one-to-one relationship between the logical volumes of the volume pairs. A volume can
be assigned only to one TC390 pair at a time. TC390 does not support operations in which one M-VOL is
copied to more than one R-VOL, or more than one M-VOL is copied to one R-VOL. Because TC390 pairs
are created on logical volumes rather than datasets, multivolume datasets require special attention. For
complete duplication and recovery of multivolume datasets, verify that all volumes of a multivolume dataset
are copied to TC390 R-VOLs and use TC390A to ensure update sequence consistency across the R-VOLs at
the remote site.
Duplicate VOLSER
The TC390 initial copy operation always copies the VOLSER of the M-VOL to the R-VOL, even if the No
Copy initial copy option is selected. For this reason, the M-VOL and R-VOL of a TC390 pair must have the
same VOLSER. Because the host operating system does not allow duplicate VOLSERs, the host system
administrator must take precautions to prevent system problems related to duplicate VOLSERs. For example,
the TC390 R-VOLs must be defined in the system generation so they do not come online automatically.
CAUTION: If the volumes that will become TC390 R-VOLs are physically attached to the same system
images as the production volumes that will become the TC390 M-VOLs, the following problems can occur:
• When a TC390 pair is established using the TSO CESTPAIR command, the secondary volume might be
online. PPRC allows this, but TC390 does not (see the following note). This could produce a duplex
secondary online to a host image, the results of which are not predictable.
• When a TC390 pair is deleted, the old secondary volume is usually offline. If a host image is IPL’d, the
operator will be offered both volumes and asked which volume should be left offline – the old duplicate
volser message. This can be confusing and is prone to error. To avoid duplication of VOLSER
1. identify the volumes that will not be accessed by the host sytem
2. perform CHP OFF or some other operation to ensure that the volumes are inaccessible.
After you complete the steps, when performing IPL, you must perform LOAD CLEAR.