HP XP P9500 Storage - Manual (Page 36)

a file between open-system platforms via a VSE dataset on an -A Data Exchange volume. In this
case, you must use the VSE record option for both transfers (FXotm/mto).
Host Access and I/O Contention
The user must manage access to the FXmto and FXotm volumes to prevent illegal I/O access contention
between the mainframe and open-system hosts. These Data Exchange volumes cannot be accessed
concurrently by the mainframe and open-system hosts, and must be varied offline from the mainframe
host during Data Exchange operations. The Data Exchange volumes should not contain any regularly
accessed data and should be dedicated to data exchange operations to avoid accidental overwriting
of data.
NOTE:
For 01-02-48 and earlier, do not access the Data Exchange volume from Data Exchange when AIX
is accessing it. For 01-02-50 and earlier, do not access the Data Exchange volume from Data Exchange
when Windows is accessing it.
NOTE:
Note the following restrictions for the listed operating systems:
• For UNIX operating systems, if the Data Exchange version is 01-02-48 and later, FXotm can run
several different datasets simultaneously.
• For Windows operating systems, if the Data Exchange version is 01-02-50 and later, FXotm can
run several different datasets simultaneously.
• For AIX operating systems, since volumes are reserved during accessing, FXotm cannot run several
different datasets simultaneously.
The Data Exchange volumes can only be accessed by open-system hosts using the Data Exchange
software. The mainframe hosts have normal read/write access to the -B and -A volumes, read-only
access to the -C volumes, and no access at all to the OPEN-x FMT volumes. The open-system hosts
have read/write access to the -C, -A, and OPEN-x FMT volumes and read-only access to the -B volumes.
The open-system hosts must use Data Exchange to access all Data Exchange volumes.
CAUTION:
Concurrent access to the Data Exchange volumes by the mainframe and open-system hosts is not
supported. The user is responsible for managing access to Data Exchange volumes to avoid I/O
contention between the mainframe and open-system hosts. Since the FCU accesses only the VTOC
area of the Data Exchange -B volumes, catalog or security control functions cannot be used to provide
access control for the 3390-3B volumes.
The mainframe host can issue a reserve command to reserve a volume for exclusive use. The
mainframe reserve command prevents access by all other hosts, including all other mainframe hosts
and all open-system hosts. The open-system host can also reserve a volume to exclude I/Os issued
by other systems. The open-system reserve command prevents access by all other open-system hosts,
but mainframe hosts still have normal access to FXmto and FXotm volumes reserved by open-system
hosts. These reserve commands affect Data Exchange operations as follows:
About Data Exchange Operations 36