Oracle Essentials [Electronic resources] : Oracle Database 10g, 3rd Edition نسخه متنی

11.6 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 11-5. Like MPP and clusters,
these systems provide scaling of memory and I/O subsystems in
addition to CPUs. A key difference is the single operating system
copy that manages the entire platform and a directory-based cache
coherency scheme to keep data synchronized. Memory access between
nodes is in the hundreds of microseconds, which is much faster than
going to disk in MPP or cluster configurations, and only slightly
less swift than local memory bus speeds in a single SMP system.

Figure 11-5. Non-Uniform Memory Access (NUMA) configuration

This enables NUMA
to have some major advantages over MPP and cluster solutions:

Parallel versions of applications don't need to be
developed or certified to run on these machines (although additional
performance gains may be realized when such applications can be tuned
for NUMA).

Management is much simpler on NUMA systems than on clusters because
there is only one copy of the operating system to manage and only one
database instance is typically deployed.

Oracle has developed on multiple NUMA platforms to provide highly
tunable Oracle versions that can take advantage of the benefits
offered. Today, Hewlett Packard Superdome and HP/Compaq AlphaServer
(GS-320) and are examples of NUMA systems with demonstrated
scalability in production databases that scale into the tens of
terabytes.