hi
can any body tell about performance tuning in DBA

Performance tuning:-
Is to find out what went wrong with the database and make corrections so that database is working fine.

For ex:-
Imagine query is taking long time to execute and DBA has to find out what is the behind that and how to overcome this problem(may be something like by creating index on a table etc)

Here are the top 10 things you can do to get the most performance out of your database. Usually, you will find that about 90% of maximum performance is achieved using about 10% of possible configuration changes. I'll discuss each item in detail in the appropriate section below (identified in parenthesis):

1. Ensure that you have enough disks (6-10 per CPU is a good start). Each table space's containers should span all available disks. Some table spaces, such as SYSCATSPACE and those with a small number of tables do not need to be spread across all disks, while those with large user or temporary tables should (Table Spaces).
2. Buffer pools should make use of about 75% (OLTP) or 50% (OLAP) of available memory (Buffer Pools).
3. Runstats should be performed on all tables, including the system catalog tables (Runstats).
4. Use the Design Advisor to recommend and review indexes for SQL workloads (Design Advisor).
5. Use the Configuration Advisor to configure the database manager and database for your application environment (Configuration Advisor).
6. Logging should occur on a separate high-speed disk, identified by the NEWLOGPATH database configuration parameter (Experimenting).
7. Concurrency can be increased by committing often (SQL statement tuning).
8. SORTHEAP should be increased to avoid sort overflows (DBM and DB configuration).
9. Table space type should be SMS for the system catalog table space, and temporary table spaces and DMS raw (device) or file for the rest. Run db2empfa to enable multi-page file allocation for the SMS table spaces; this will allow SMS table spaces to grow an extent at a time (instead of a page), which can speed up heavy insert operations and sorts which spill to disk (Table spaces).
10. Use parameter markers for repeated statements (SQL statement tuning).