IBM eServer zSeries 990 Technical Guide

176 IBM ^ zSeries 990 Technical Guide

Figure 7-10 shows how a GDPS/PPRC Cross-site extended distance Parallel Sysplex can be

established with RPQ 8P2263.

Figure 7-10 Cross-site extended distance for Parallel Sysplex and GDPS/PPRC

7.4.2 GDPS/XRC

XRC is a combined hardware and software asynchronous remote copy solution. The

application I/O is signalled completed when the data update to the primary storage is

completed. A DFSMS component, called System Data Mover (SDM), asynchronously

offloads data from the primary storage subsystem’s cache and updates the secondary disk

volumes in the recovery site.

The GDPS solution based on XRC, referred to as GDPS/XRC, has the attributes of a Disaster

Recovery solution.

In GDPS/XRC, the production system(s) can be a single system, multiple systems sharing a

disk, or a base or Parallel Sysplex cluster1. GDPS/XRC provides 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 full data integrity across multiple volumes and storage subsystems, and the

ability to perform a normal Data Base Management System (DBMS) restart - not DBMS

recovery - at the opposite site. GDPS/XRC is application-independent and therefore covers

the customer's complete application environment.

Restriction: The maximum distance between a pair of Sysplex Timers in an Expanded

Availability configuration remains at 40 kilometers (25 miles). To achieve 100 kilometers

distance between sites, one option is to consider an intermediate site at less than 40

kilometers from one or the other site or to place two Sysplex Timers in one site.

Note: In Figure 7-10, the midspan 9037 can also be located within 40 km of site 2 or on the

South path; All ETR and CLO links are provisioned as one channel per wavelength.

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Site 1 Site 2

100 km

D

W

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CPC CPC

hut with

amplifiers

1 ETR link

per CPC

Route A

Route B

ETRETR

CLO

2 CLO

Links

1 ETR

link per

CPC

1 ETR

link per

CPC

40 km max 40 km nom

ETR

ETR

ETR

ETR

ETR

CLO

9037

9037