What do you consider basic techniques that all DBAs should know and be doing?
At a bare minimum, DBAs should be comfortable running user-managed hot and cold backups, as well as database exports and imports. The next level to pursue then becomes getting proficient with RMAN backup and recovery. In Oracle 10g, DBAs should begin using Data Pump since it has more functionality than export/import and can provide a boost in performance. What's the difference between a basic plan and an advanced one?
A basic plan ensures that your databases can be recovered in at least one or two ways. It includes cold or hot backups and perhaps database exports, as well as a disaster recovery (DR) plan. A more advanced plan takes into account database availability, performance and backup/recovery of very large databases. An advanced plan makes use of RMAN as well as Data Guard functionality. Can you describe a few advanced techniques?
An example of an advanced plan is one where Service Level Agreements (SLAs) are developed with the business to determine backup and recovery requirements. RMAN full and incremental backups could then be used in a cyclical manner over a specified time period (say, a week or month) so that backup and restore windows meet these SLAs. Restores would be regularly tested to ensure that procedures are correct and that the DBAs are ready for the day they need to perform that emergency recovery! One or more standby databases could be created at DR sites recovering at different delay intervals. What are some differences in backup and recovery techniques in 9i and 10g compared to earlier releases?
There have been major improvements with both the 9i and 10g releases. Before these, we had user managed backups as well as standby databases, RMAN and Export/Import. 9i and 10g then brought major improvements in RMAN, Data Guard, Data Pump and Flashback functionality. RMAN ease of use and scalability have improved greatly since 8i. Closely tied functionality between RMAN backups and copies is another major improvement. An example of this is the ability to apply incremental backups to an RMAN copy. RMAN binary compression is another nice new feature.
Data Guard has improved the manageability of standby databases greatly. The ability to perform graceful failover, as well as four different protection levels, has made this a feature that many production installations are now using.
Flashback technology and Data Pump underscore the need for increased availability, functionality and performance. Combining Flashback, Data Pump, RMAN and Data Guard into a comprehensive backup strategy is an approach that DBAs will use with 10g. How has the DBA's role in the backup and recovery plan changed as a result of those improvements?
We need to think of this differently than we have in the past. For example, terabyte databases take more time to backup and recover just when business is demanding higher availability. We need to find ways to avoid or at least minimize the need to perform restores and recoveries. Performing as many operations online as possible should be our goal. Disaster recovery and backup/recovery are merging into a single strategy with Data Guard and standby databases providing DBAs with a way to keep databases up and running across sites. Our goal should be to minimize maintenance and maximize availability and performance. What's the worst thing a DBA can do (or not do)?
There are two things that a DBA should avoid. The first is to not become complacent and keep doing things the same way. There are new ways to perform backup/recovery and new requirements brought on due to database size and availability needs. DBAs need to keep up with all of the latest features so the appropriate ones can be used for new applications.
The second is to not practice recoveries. Even seasoned DBAs need to continually practicing backups and recoveries to keep their skills sharp and to ensure that the procedures being used still work. There is nothing worse than having to perform a critical recovery when you aren't sure it will work. What are five backup and recovery dos and don'ts that every DBA should know?
The five things that every Oracle DBA should be familiar with are (and these are in no particular order):
- User managed hot and cold backup/recovery
- Data Guard and Standby databases
- Data Pump including transportable tablespace features
- Flashback technology