Saturday, August 25, 2012

File system layout to minimize disk drive contention

This example configuration contains eight data areas, including disk drives, striped sets,
RAID sets, and placeholders for other new technologies to be developed in the future.
Separate the eight data areas as completely as possible. Ideally, operate from different
device controllers or channels to maximize throughput. The more disk drive heads are
moving at one time, the faster the database. To minimize disk drive contention, lay out
the file system disk drives as follows:
  • AREA 1 – Oracle executables and a control file
  • AREA 2 – Data: datafiles, index datafiles, system datafiles, tool datafiles, user datafiles,
    and a control file
  • AREA 3 – Data datafiles, index datafiles, temporary datafiles, undo datafiles, and a
    control file
  • AREA 4 – Archive log files, export files, backup staging area, and a control file
  • AREA 5 – Redo log files
  • AREA 6 – Redo log files
  • AREA 7 – Redo log files
  • AREA 8 – Redo log files
Online redo log files exist on four separate disk drives. Online redo log files are
multiplexed, and Oracle creates these log files in a circular fashion:
redo log 1 =>redo log 2 => redo log 3 => redo log 4 =>redo log 1
As a result, the I/O is evenly distributed. Therefore, when Oracle switches log file
groups, writing to the new redo log files does not impact reading the old redo log file
to create a new archive log file.

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