HP StorageWorks XP Remote Web Console Software - Manual (Page 47)

Hitachi TrueCopy for z/OS user guide 47
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.
• To avoid these problems, HP strongly recommends that the user specify OFFLINE=YES if the secondary
volumes are to be generated in the production host’s IOCP and system generation.
NOTE: If you cannot create a pair because the TC390 R-VOL is online with hosts, all paths must be offline
from all hosts. If you cannot identify the hosts that are online, please contact your HP account support
representative.
Logical Volume Image (LVI)
TC390 supports basic mainframe LVIs that can be configured on the XP12000/XP10000 (for example,
3390-3, -3R, -9, or -L). TC390 does not support multiplatform volumes (3380-J,E,K type A,B or C, or
3390-1,2,3 type A, B or C). TC390 can copy data between volumes with the same emulation and capacity
(for example, 3390-3R to 3390-3R), and can also copy from smaller volumes to larger volumes (for
example, 3390-3 to 3390-9) of the same emulation (VTOC expansion must be used). TC390 also supports
the Virtual LVI/LUN feature of the XP12000/XP10000 to establish TC390 pairs with custom-size LVIs as
well as standard-size LVIs. When custom-size LVIs are assigned to TC390 pairs, the R-VOL must have the
same or larger capacity than the M-VOL. TC390 displays the LVI of the M-VOLs and R-VOLs.
NOTE: The host I/O time-stamping function is not supported by 3380 LVIs. If you plan to use TC390A
pairs, the TC390A M-VOLs and R-VOLs must be 3390 LVIs.
In the case that M-VOL or R-VOL is 3390-L LVI under the connection of the disk array, and the number of
cylinders is more than 10,017, the capacity of the M-VOL and R-VOL must be the same.
CAUTION: If you use TC390 to copy from a smaller volume to a larger volume, you will not be able to
perform TC390 operations in the reverse direction (from the secondary site to the primary site) after a
disaster has occurred and the secondary site was used for production. This restriction exists because
TC390 does not support copying from a larger volume to a smaller volume. HP strongly recommends that
this capability (copying from a smaller volume to a larger volume) only be used for data migration
purposes.
CAUTION: If you use a Fujitsu operating system, and utilize TC390A to copy from a smaller capacity of
M-VOL to the larger capacity of R-VOL, an error will occur when the write operation will be performed to
the former R-VOL after the pair has been deleted. If the write operation is required on this volume, make the
capacity of M-VOL and R-VOL same, and then create a pair.