||Oracle Tips by Burleson
Disk I/O Tuning
Chapter 1: General Disk Architecture
hasn't changed in the general sense in the last seventeen or so
years. Disks have gotten smaller and faster but their general
features have not changed that much. Disks are physical entities
consisting of some dimensionally stable substrate overlayed (usually
aluminum alloys but now magnesium and even glass or ceramics are
being considered) with a thin layer of material that can take and
hold a magnetic charge. Optical media uses laser gouged pits to
indicate zero or one rather than the presence or lack of magnetic
signals; the mechanical technology is essentially the same in either
magnetic or optical media. This general magnetic disk structure is
shown in figure 1-1.
Figure 1-1: General magnetic disk structure
magnetic disk an electromagnet is used to place or remove magnetic
charges to the magnetically sensitive coating. These magnetic
charges are later read by a read head that senses the magnetic
charge. Naturally the closer to the disk that the head fly the
weaker, and thus more dense, the signals can be.
The above text is
an excerpt from:
Oracle Disk I/O Tuning
Disk IO Performance & Optimization for Oracle
by Mike Ault
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