Oracle Optimal Flexible Architecture
Oracle Tips by Burleson Consulting
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Optimal Flexible Architecture (OFA) standard.
In accordance with the Oracle
National Technical Response Team, the OFA process involves the following three
Establish an orderly operating system
directory structure in which any database file can be stored on any disk
Name all devices that might contain
Oracle data in such a manner that a wild card or similar mechanism can
be used to refer to the collection of devices as a unit.
Make a directory explicitly for
storage of Oracle data at the same level on each of these devices.
Beneath the Oracle data directory on
each device, make a directory for each different Oracle database on the
Put a file X (X is any database
file) in the directory /u??/ORACLE/sid/type_desig (or on W2K or NT:
C:\oracle\sid\type_desig) if and only if X is a control file, redo log
file, or datafile of the Oracle database whose DB_NAME is sid. The
type_desig specifies the type of file to be placed in the directory at
that location and is usually data, index, control or redo.
You may wish to add an additional directory layer if
you will have multiple Oracle versions running at the same time. This
additional layer includes the version level.
Separate groups of segments (data objects)
with different behavior into different tablespaces.
Separate groups of objects with
different fragmentation characteristics in different tablespaces (e.g.,
donít put data and rollback segments together).
Separate groups of segments that
will contend for disk resources in different tablespaces (e.g., donít
put data and indexes together).
Separate groups of segments
representing objects with differing behavioral characteristics in
different tablespaces (e.g., donít put tables that require daily backup
in the same tablespace with ones that require yearly backup).
Maximize database reliability and
performance by separating database components across different disk resources. A
caveat for RAID environments: Consider spreading datafiles across multiple
controller volume groups.
Keep at least three active copies of
a database control file on at least three different physical arrays.
Use at least three groups of redo
logs in Oracle9i. Isolate them to the greatest extent possible on
hardware serving few or no files that will be active while the RDBMS
(relational database management system) is in use. Shadow redo logs
Separate tablespaces whose data will
participate in disk resource contention across different physical disk
resources. (You should also consider disk controller usage.)
Minimum OFA Configuration
The minimum suggested configuration would consist of seven data
areas: disks, striped sets, RAID sets, or whatever else comes down the pike in
the next few years. These areas should be as separate as possible, ideally
operating off of different device controllers or channels to maximize
throughput. The more disk heads you have moving at one time, the faster your
database will be. The disk layout should minimize disk contention. For example:
AREA1. Oracle executables and user areas, a control
file, the SYSTEM tablespace, redo logs
AREA2. Data-datafiles, a control file, tool-datafiles,
AREA3. Index-datafiles, a control file, redo logs
AREA4. Rollback segment-datafiles
AREA5. Archive log files
AREA6. Export files
AREA7. Backup staging
Of course, this is just a start; you might find it wise to add
more areas to further isolate large or active tables into their own areas as
well as to separate active index areas from each other.
The structure on UNIX could look like the following:
/oracle0/product/oracle/9.0.1/ Top level $ORACLE_HOME
distribution structure under version
/oracle0/data/ Place instance names under type
pfile/ initialization file
location (linked back to dbs directory)
create/ Database creation
script storage area
Using this type of structure even on a RAID5 volume allows for a
logical separation of files for ease in locating and controlling database files.
For other platforms just alter the directory syntax; for example, on NT the
/oracle0/product/oracle/9.0.1 directory becomes
I have seen several questions posted as to why the standard says
to use u01, u02, and so on for mount points. This based in old UNIX naming
conventions and has little actual usefulness in modern structures. Call the
mount points whatever you wish as long as it meets your requirements. I suggest
using the application name, for example.