IBM z/OS - page 40

On the other hand, the GDPS solution based on Extended

Remote Copy (XRC), referred to as GDPS/XRC, has the

attributes of a Disaster Recovery solution. XRC is a com-

bined hardware and software asynchronous remote copy

solution. The application I/O is signaled completed when

the data update to the primary storage is completed. Sub-

sequently, a DFSMSdfp™ component called System Data

Mover (SDM), typically running in site 2, is designed to

asynchronously ofﬂ oad data from the primary storage sub-

system’s cache and updates the secondary disk volumes.

In GDPS/XRC, the production system(s) located in site 1

can be a single system, multiple systems sharing disk, or

a base or Parallel Sysplex cluster. GDPS/XRC is designed

to provide a single, automated solution to dynamically

manage storage subsystem mirroring (disk and tape)

to allow a business to attain “near transparent” disaster

recovery with minimal data loss. GDPS/XRC is designed to

provide the ability to perform a controlled site switch for an

unplanned site outage, maintaining data integrity across

multiple volumes and storage subsystems GDPS/XRC is

designed to be application independent and therefore is

capable of covering the customer’s complete application

environment.

GDPS requires Tivoli® NetView® for z/OS or Tivoli NetView

for OS/390, Tivoli System Automation for OS/390, and

remote copy technologies.

Note: Dark ﬁ ber refers to dedicated strands of ﬁ ber optic

cable with no electronics between the ends (source and

destination).

Geographically Dispersed Parallel Sysplex HyperSwap™

The GDPS/PPRC HyperSwap function is designed to

broaden the continuous availability attributes of GDPS/

PPRC by extending the Parallel Sysplex redundancy to

disk subsystems. The HyperSwap function can mask

planned and unplanned disk and site reconﬁ gurations

by transparently switching to use the secondary PPRC

volumes. The HyperSwap function is designed to be con-

trolled by complete automation, allowing all aspects of the

site switch to be controlled via GDPS.

The HyperSwap function planned provides the ability to

transparently switch all primary PPRC disk subsystems

with the secondary PPRC disk subsystems for a planned

switch conﬁ guration. It enables disk conﬁ guration mainte-

nance and planned site maintenance without requiring any

applications to be quiesced. Large conﬁ gurations can be

supported, as HyperSwap has been designed to provide

capacity and capability to swap large numbers of disk

devices very quickly. The important ability to re-synchro-

nize incremental disk data changes, in both directions,

between primary/secondary PPRC disks is provided as

part of this function.

The unplanned HyperSwap function contains additional

function designed to transparently switch to use second-

ary PPRC disk subsystems, in the event of unplanned

outages of the primary PPRC disk subsystems or a failure

of the site containing the primary PPRC disk subsystems.

With unplanned HyperSwap function, disk subsystem

failures no longer constitute a single point of failure for

an entire sysplex. If applications are cloned and exploit-

ing data sharing across the two sites, the GDPS/PPRC