With a full understanding of Oracle 11g's capabilities and how you plan to exploit them, it is time to plan the upgrade. But do you carry out an in-place upgrade or a migration upgrade? This section examines the pros and cons of each
Read the other sections of this guide on servers for Oracle upgrades:
Comparing servers for Oracle database 11g upgrades
Oracle database upgrades: the in-place vs. migration upgrade decision
Choosing the right server hardware is all about choosing the right software
The best of the Oracle 11g-ready servers
Can Sun shine running Oracle 11g?
There are two paths to follow when it comes to upgrading an Oracle database. Some administrators may choose to do an "in-place" upgrade, where the new version of Oracle is installed on the same server as the existing version. Other administrators may choose to do a "migration" upgrade, where the new version of Oracle is installed on new hardware and the data is migrated from the old version to the new version. At first blush, an in-place upgrade looks to be a simpler, faster method to accomplish an Oracle upgrade, but there are several downsides to pursuing that method.
First, an in-place upgrade introduces more downtime and the Oracle database will not be available during the whole upgrade process. Testing an in-place upgrade can prove to be more difficult because administrators have to work with live data and take the database offline while testing the upgrade and/or the upgrade process. Also, an in-place upgrade often incurs a performance penalty. Newer versions of software products tend to have higher hardware demands which affects their performance.
In-place upgrades are difficult to undo, if there is a significant problem with the upgrade or data corruption is encountered, going back to the previous database and pre-upgrade state requires a lengthy restore from the backup process. In short, an in-place upgrade often takes more man hours and can create additional tasks, which may be difficult to budget for and also leaves little room for failures or other problems. The money saved by not purchasing new hardware is often spent on man hours and upgrade tasks and can exceed the cost of replacement hardware.
Although there are additional hardware costs with a database migration upgrade, the benefits far outweigh the additional costs. Obviously, one of the major advantages comes in the form of speed. Newer hardware will most likely be faster than the older hardware being replaced. There is also a reliability factor to consider. New hardware will be under warranty and will by nature be more reliable than older hardware.
New hardware also allows concurrent upgrades to be performed. For example, with an implementation of a new server, the latest operating systems, device drivers and support software can be included, often bringing additional features and improved performance. What's more, newer hardware tends to have better built-in management capabilities, such as Intel's VPRO or other types of lights-out management features.
New hardware proves to be beneficial for the overall upgrade process by simply offering a clear path to perform an upgrade. Because the old hardware does not have to be modified in any way; the existing database remains available if there is a problem performing an upgrade. New hardware also provides a method to perform practice upgrades and test the viability of those upgrades. After weighing the pros and cons of the new hardware versus in-place-upgrade processes, most administrators will find that the new hardware upgrade path is a better choice.