IBM Enterprise Storage Server 2105 E10, Introduction And Planning Manual

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The PPRC feature requires that you install ESCON adapters on the ESS. The
ESCON adapter provides the link between a primary and a secondary server. More
than one ESCON link increases the reliability and availability of the PPRC feature.
You can use the ESS Web Copy Services interface to:
v
Initiate and terminate the functions
v
Suspend a copy operation
v
Query the status of volumes
v
Perform predefined tasks
Also, with PPRC, a recovery host has the ability to recover control of the secondary
volume.
For System/390 hosts you can use TSO to invoke these functions for MVS. For the
procedures for using TSO for PPRC functions, see
DFSMS/MVS V1 Remote Copy
Guide and Reference
.
For open system hosts you can use the ESS Web Copy Services command-line
interface to invoke these functions. For more information on the command-line
interface see the
IBM Enterprise Storage Server Host Systems Attachment Guide .
See “FlashCopy and PPRC restrictions for open system hosts” for additional
information about PPRC.
FlashCopy and PPRC restrictions for open system hosts
When you copy a source volume to a target volume with FlashCopy or PPRC, and
you require concurrent read/write access of both volumes, the source and target
volumes should be on different host systems. A copy operation with the source and
target volume on the same host system creates a target volume with the same
identification as the source volume. The host system sees two identical volumes.
When the copy process creates the same identification for the target volume as for
the source volume the user cannot distinguish one from the other, so the user may
not be able to access the original data.
Note: For some operating systems, such as Novell NetWare, the user is unable to
access either the source or target volume. Although both data sets are intact,
they are invisible to the user.
The target volume and the source volume can be on the same host system for a
PPRC or FlashCopy operation only under the following conditions:
v
For AIX: when the host system is using a Logical Volume Manager (LVM) with
recreatevg command support
v
For AIX, SUN, and HP: when the host system is not using an LVM
v
For any host system: when the host system can distinguish between a source
and a target volume that have the same identification
UNIX, Windows NT, and Windows 2000 availability features
This section describes UNIX, Windows NT, and Windows 2000 availability features,
which include:
v
Data sharing
v
IBM Subsystem Device Driver
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ESS Introduction and Planning