IBM eServer zSeries 900 Technical Guide

188 IBM eServer zSeries 900 Technical Guide

򐂰 PPRC (Peer-to-Peer Remote Copy) architecture

򐂰 XRC (Extended Remote Copy) architecture

򐂰 Virtual Tape Server Remote Copy architecture

GDPS supports both the synchronous (PPRC) as well as the asynchronous (XRC) forms of

remote copy.

There is new Enhanced HMC support for GDPS/PPRC and GDPS/XRC configurations.

GDPS/PPRC and GDPS/XRC configurations are significantly enhanced in terms of

availability and simplified configuration. These enhancements are made available for GDPS

configurations by use of new operating system support, which is designed to eliminate the

need for a previously required workstation in the GDPS configuration, thus simplifying the

configuration. This support is available with IBM zSeries driver 3G and IBM G5/G6 driver 26,

with current maintenance levels, and z/OS V1.2 and later with the service defined in the PSP

Bucket for MSYSOPS.

5.4.1 GDPS/PPRC

GDPS/PPRC is a hardware solution that synchronously mirrors data residing on a set of disk

volumes, called primary volumes in the application site, to secondary disk volumes on the

second system at another site. Only when the application site storage subsystem receives

“write complete” from the recovery site storage subsystem is the I/O signaled as completed.

The physical topology of a GDPS/PPRC consists of a base or Parallel Sysplex cluster spread

across two sites (site A and site B) separated by up to 40 km (approximately 25 miles), with

one or more z/OS and/or OS/390 systems at each site; see Figure 5-5 on page 189. The

multisite Parallel Sysplex cluster must be configured with redundant hardware (for example, a

Coupling Facility and a Sysplex Timer in each site), and the cross-site connections must be

redundant.

All critical data resides on storage subsystems in site A (the primary copy of data) and is

mirrored to site B (the secondary copy of data) via PPRC synchronous remote copy.

The new 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 GDPS/PPRC hyperswap function provides the ability to transparently switch all primary

PPRC disk subsystems with the secondary PPRC disk subsystems for a planned switch

reconfiguration. Planned for release in the second half of 2002, it is designed to provide the

ability to perform disk configuration maintenance and planned site maintenance without

requiring any applications to be quiesced.

GDPS/PPRC provides the following benefits:

򐂰 Continuous availability

򐂰 Near transparent disaster recovery

򐂰 Recovery Time Objective (RTO) less than an hour (will be a minute with hyperswap).

򐂰 Recovery Point Objective (RPO) of zero (optional)

򐂰 Protects against metropolitan area disasters

GDPS/PPRC hardware requirements

GDPS/PPRC requires the following hardware configuration:

򐂰 The multisite Parallel Sysplex cluster must be configured with redundant hardware across

both sites.

Chapter 5. Sysplex functions 189

򐂰 The systems in a Parallel Sysplex cluster must have full connectivity (CTC connectivity, CF

XCF connectivity, or both) for Parallel Sysplex cluster communication.

򐂰 The systems must be attached to a Sysplex Timer (IBM 9037 Model 2) in the expanded

availability configuration.

򐂰 Primary couple data sets—including the Parallel Sysplex cluster, automatic restart

manager (ARM), coupling facility resource management (CFRM), system logger (LOGR),

Parallel Sysplex cluster failure manager (SFM), and workload manager (WLM)—must

reside at site A and the alternate couple data sets reside at site B.

򐂰 Each system must have its own set of disks for system-related data sets/volumes (such as

system residency volume, master catalog, paging volumes, LOGREC data sets, and SMF

data sets) because each site must be able to function if access is lost to the storage

subsystems in the other site.

򐂰 Storage subsystem with PPRC level 2 (includes the Freeze function) is required.

GDPS/PPRC software requirements

GDPS/PPRC requires the following software:

򐂰 z/OS Version 1 Release 1 or higher

򐂰 Tivoli Netview for OS/390 Version 1 Release 2 or higher

򐂰 System Automation for OS/390 Version 1 Release 2 or higher

Figure 5-5 GDPS/PPRC

GDPS hyperswap

With GDPS/PPRC hyperswap function, the speed of GDPS site reconfigurations can be

significantly improved. Stage 1 of the hyperswap function, available with GDPS 2.7 in the

second half of 2002, provides the ability to transparently switch all primary PPRC disk

subsystems with the secondary PPRC disk subsystems for a planned switch reconfiguration.

CF01 CF02

Application

Systems

Recovery

Systems

Site A

Site B

Network

High Performance

Routing

Remote copy

(PPRC)

40km max with

IBM Fiber Saver

A

Copy

B

B

Copy

A

1

2

3

4

5

6

7

8

9

10

11

12

1

2

3

4

5

6

7

8

9

10

11

12

SW

SW