Oracle: OFA Part 2

Dear Readers,

My name is Franz Devantier, creator of this blog.  I am an Oracle Certified Professional (OCP DBA 11g) Security DBA.  I will be sharing with you the basic duties of an Oracle DBA, and also some of the undocumented, and not so well known tasks. 

OFA – Optimal Flexible Architecture

(Part 2, Operating System Configuration)

OFA – Note 1

Name the mount points in such a way, that you get an idea of the contents by looking at the name.

For example:  /AB

A -: Site-Specific identifier

B -: Content-Specific identifier

On Salaris /etc/vfstab;  shows the mapping of mount point names to device names.  Each row in the vfstab represents the mapping of the mount point to a device name/disk slice. 

On windows it will be something like Drive’s C:  D:  E:  F:  G:

If two or more applications live together in the same mount point or drive, obviously not in the same directory, but a sub-tree of the mount point/drive directory.  Then the base directory, should not name one application and not the other.

For example if the sub-tree directories contained <datafiles> on one branch and <datapump> on another branch, then the name of the root directory should describe as far as possible, both the sub-trees content, and not just one to the other, or a neutral alternative.

“/oracle/datafiles” would give the impression that there were only oracle files involved; and “/backups/datapump” would create the impression that there were only backup files in this structure.

So you would need a neutral base directory name like /u01 or /u02.  “/u02/oracle/datafiles”  and “/u02/backups/datapump”.  Now there is no need to become confused, and make an expensive mistake.

Storing files from two or more databases, on the same drive; compromises the best practice of avoiding performance bottlenecks.  The best practice of minimizing the impact of disk failure is also compromised, because now you stand to lose more than one database, if you lose one disk.

To minimize performance bottlenecks, with multiple databases on one computer, you will need to install additional hard drives.  To minimize the impact from disk failure, you will also need to install additional hard drives.  Without additional resources, your database environment is compromised.  The best thing to do in such a case is to prepare a document, describing the level of risk that the business is taking with their database installation.  If the business decides not to provide the needed hardware resources, then you must keep your email correspondence for when the disk fails; so that you can prove, that you did warn them about the possibility.

Remember that mount points abstract the underlying hardware, as don’t name them in such a way as to mirror the underlying hardware.

Login Home Directories

On the older UNIX computers, home directories were placed in “/usr”.  The problem with this arrangement, is that the entire “/usr” sub-tree structure may be replaced during upgrades.

A better login home directory would be “/u” or “/home”.  Properly sizing of file systems or drives will make things run a lot smoother in the long term operation of a database installation.

In Oracle apps (ebiz), the content of the database and application has grown bigger and bigger in time.  It is even more important to properly size the hardware, before we start installing Oracle.  With VLDB installations where the databases are in excess of a few Terabytes, and moving up towards a few hundred Terabytes; it becomes even more important to properly design the Oracle Database  installation.

Best practise requires that it is possible to exchange hardware components, without having to rebuild the applications that refer to these hardware components.

OFA Standard 5; requires that it is possible to distribute the collection of home directories as well as the contents of an individual home directory, across two or more disk drives.

Franz Devantier,

Need a database health check?

devantierf@gmail.com

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