Each component also has limited capacity.
The CPU and the Level 1 (L1) memory cache on the CPU have the lowest latency, as
shown in Table 12-1, but also the least capacity. Disk has the most capacity but the
highest latency.
There are several different types of memory: an L1 cache, which is on
the CPU chip; an L2 (Level 2) cache on the CPU surface, an L3 cache
on the same board as the CPU; and main memory, which is the
remaining memory on the system accessible through the memory bus.
Table 12-1. Typical sizes and latencies of system components
Element Typical storage capability Typical latency
CPU None None
L1 cache (on CPU) 10s to 100s of KBs 10 nanoseconds
L2 cache (on CPU surface) Single MBs 40??“60 nanoseconds
L3 cache (on same board) 10s of MBs 120 nanoseconds
Main memory MBs to TB+ 1,000 - 10,000 nanoseconds
Disk GBs to hundreds TBs 1-10 million nanoseconds
292 | Chapter 12: Oracle and Hardware Architecture
An important part of tuning any Oracle database involves reducing the need to read
data from sources with the greatest latency (e.
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