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

2-58 About TrueCopy for z/OS Operations
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
ShadowImage for z/OS (SIz)
SIz volumes can be assigned to TCz pairs, and TCz volumes can be assigned
to SIz pairs. For further information on ShadowImage for z/OS, please refer to
the ShadowImage for IBM z/OS User's Guide.
Note: When TCz and ShadowImage for z/OS are both active on the same
USP V, TCz cannot be used to copy within that storage system. ShadowImage
for z/OS is recommended for storage system-internal copy. If ShadowImage
for z/OS is not active, TCz Synchronous supports intra-storage system copy
and requires at least one external fibre cable loop.
TrueCopy for z/OS and ShadowImage for z/OS can be used together in the
same storage system and on the same volumes to provide multiple copies of
data at the main and/or remote sites. Table 2-16 describes the host pair
status reporting for TCz volumes, SIz volumes, and TCz/SIz shared volumes.
Table 2-17 shows the currency of the data on a shared TCz/SIz volume based
on TCz and SIz pair status.
• For shared TCz/SIz volumes, the TCz pair status is reported to the host if you
query the TCz R-VOL. To obtain the SIz pair status, query from the host:
– the SIz T-VOL status of the SIz pair if the SIz S-VOL and TCz M-VOL share
the same volume
– the SIz T-VOL status of the SIz pair if the SIz S-VOL and TCz R-VOL share
the same volume
– the SIz S-VOL status of the SIz pair if the SIz T-VOL and TCz M-VOL share
the same volume.
• ShadowImage for z/OS supports multiple target volumes (T-VOLs) for each
source volume (S-VOL). If you issue a pair status query to a SIz S-VOL (e.g.,
CQUERY), the status for only one SIz pair is reported (the pair with the T-VOL
with the lowest LDEV ID). To obtain the pair status for the SIz pair(s) with
the other T-VOL(s), you must direct the host query to the specific T-VOL
using the T-VOL’s LDEV ID in the host command (e.g., CQUERY DEVN
parameter). The ShadowImage for z/OS software displays the LDEV ID and
SIz pair status of all T-VOLs associated with an S-VOL.