Entries tagged as Oracle DBA
Difference between DBFile Sequential and Scattered Reads
What is the difference between DBFile Sequential and Scattered Reads? Â Both “db file sequential read” and “db file scattered read” events signify time waited for I/O read requests to complete. Time is reported in 100′s of a second for Oracle 8i releases and below, and 1000′s of a second for Oracle 9i and above. Read More...
Tune Oracle Wait events
How does one tune Oracle Wait events? Â Some wait events from V$SESSION_WAIT and V$SYSTEM_EVENT views: Event Name: Tuning Recommendation: db file sequential read Tune SQL to do less I/O. Make sure all objects are analyzed. Redistribute I/O across disks. buffer busy waits Increase DB_CACHE_SIZE (DB_BLOCK_BUFFERS prior to 9i)/ Analyze contention from SYS.V$BH log buffer Read More...
Manage Oracle database users
How does one manage Oracle database users? Â Oracle user accounts can be locked, unlocked, forced to choose new passwords, etc. For example, all accounts except SYS and SYSTEM will be locked after creating an Oracle9iDB database using the DB Configuration Assistant (dbca). DBA’s must unlock these accounts to make them available to users. Look Read More...
Common RMAN errors
What are the common RMAN errors (with solutions)? Â Some of the common RMAN errors are: RMAN-20242: Specification does not match any archivelog in the recovery catalog. Add to RMAN script: sql ‘alter system archive log current’; RMAN-06089: archived log xyz not found or out of sync with catalog Execute from RMAN: change archivelog all Read More...