File placement for a Producton Database
In a production database environment, you should never place all of your database files on one disk. There are two fundamental reasons for this:
- The safety of an Oracle database depends on having more than one copy of both the control files and the redo log files. These are placed on separate disks, so that if any one disk is lost, the database can be recovered using the other copies. Placing all the files on one disk ensures that losing the disk causes you to lose everything
- The second reason to use multiple disks involves performance. A single disk can only sustain so much throughput, and it probably won't be enough for any serious application. Spreading your database files around between disks and controllers distributes the I/O load and increases the throughput.
This lesson has you place all the control files for the COIN database on one disk. I did that because it's reasonable to assume that most of you are working through this course using a Windows workstation with only one disk drive. In a more realistic work situation, the configuration for the control files might look like this:
Control_files: c:\oracle\oradata\COIN\control01.ctl,
d:\oracle\oradata\COIN\control02.ctl,
e:\oracle\oradata\COIN\control03.ctl
Notice that all the files are on separate disks. In this situation, if any one disk is lost, you still have two copies of your control files.
For those of you working in UNIX environments, it is important to work closely with your system administrator to understand how the physical disk is set up on your system.
UNIX allows for a great deal of flexibility in how storage is used, and the relationship of a UNIX mount point
to the underlying physical drives is not always obvious.