Server is too slow

Question

I have oracle 9i database on sun solaris OS
IBM server.
2GB RAM
4 hard disk
45 users are login in to the system.
Its almost dead slow and some time user get out from the system.It is almost in hold sitution.
When ever we restart the server all the process clear and works properly.After some time its started slow and performance got detoriate.
gradualy its gets slow by the time and one point time it is dead slow and takes 30 min to commit transaction.which takes 20 sec at normal time.When i restart server it works normaly but gradually it gets slow again.
please write some procedure to checkup
database configuration is standard

Answer 1

You should use statspack to check what are the main waits.
Some indicators to check :
- too many fts/excessive IO => check sql statements (missing index, wrong where clause)
- explain plan for most important queries : using cbo or rbo ? If cbo, statistics should be up to date. If rbo, check acces path.
-excessive logfile switch (> 5 per hour) : increase logfile or disable logging
- undo waits => not enough rollback segments (if you don't set AUM)
- data waits => alter initrans, pctfree, pctused
- too many chaining rows => rebuild set of datas or rebuild table
- too many levels in indexes => rebuild index
- excessive parsing : use bind variable or alter parameter cursor_sharing
- too many sort on disks => increase sort_area_size and create others temporary tablespace on separate disks
- too many blocks reads for a row => db_block_size too few or too many chaining rows
- too many lru contention => increase latches
- OS swapping/paging ?
Too improve performance :
- alter and tune some parameters : optimizer_mode, sort_area_size, shared_pool_size, optimizer_index_cost_adj, db_file_multiblock_read_count...
- keep most useful packages in memory
- gather regularly statistics (if using cbo)
How do your users access to the db ?
Jean-François Léguillier
Consultant DBA