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.
1
12
2
3
4
5
6
7
8
9
10
11
1
12
2
3
4
5
6
7
8
9
10
11
Site 1 Site 2
100 km
D
W
D
M
D
W
D
M
D
W
D
M
D
W
D
M
D
W
D
M
D
W
D
M
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

Get IBM eServer zSeries 990 Technical Guide now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.