||Oracle Tips by Burleson
Disk I/O Tuning
Chapter 1: General Disk Architecture
rotational latency is related to the speed at which the disk
rotates. There is also the positional latency which is mostly
determined by how fast the disk actuator can move. These combined
latencies form the basis for the seek times for the drives. Seek
times generally determine how fast data can be retrieved from a
a magnetic drive the read/write head(s) float over the disk surface
on the long actuator arm. Sudden physical shocks can cause the
actuator arm to flex causing the read-write heads to momentarily
make contact with the disk surface. The effects of the read-write
heads coming in contact with the surface of a disk vary from little
damage and no loss of data to a severe disk crash with loss of all
data unless sophisticated and expensive disk recovery processes are
used. I have seen disk failures (head crashes) where the magnetic
media was gouged off down to the aluminum substrate.
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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