Clustered solutions might also be deployed where high
availability is desired. On Windows clustered platforms, Oracle Fail Safe might be
chosen as an alternative to RAC, although data is not shared by the two systems and
the second system provides only standby access to this data. Because concurrent
access isn??™t provided, the Fail Safe solution doesn??™t offer the scalability that Real
Application Clusters can provide.
Clusters | 297
In earlier editions of this book, we described a very high-end variation of clusters
known as a massively parallel processing (MPP) system. Such systems were essentially
a cluster in a box with nodes connected via very high-speed and proprietary
networks (see Figure 12-4). Open-systems vendors now rarely sell such platforms
since clusters of lower-cost system components (nodes) have displaced them in the
broader marketplace.
Figure 12-4. Massively parallel processing (MPP) system
Node 1
CPU CPU
L2 L2
Memory
I/O
Disk
Node 3
CPU CPU
L2 L2
Memory
I/O
Disk
Node 2
CPU CPU
L2 L2
Memory
I/O
Disk
Node 4
CPU CPU
L2 L2
Memory
I/O
Disk
High-Speed Interconnects
Typical MPP Switch
High-Speed Interconnects
298 | Chapter 12: Oracle and Hardware Architecture
Non-Uniform Memory Access Systems
Non-Uniform Memory Access (NUMA) computers, introduced in the mid-1990s,
provide even greater throughput than SMP by linking multiple SMP components via
distributed memory, as shown in Figure 12-5.
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