Oracle Database Administration Blog » aarthimudhalvan

Command to find files created a day before

aarthimudhalvan — Tue, 07 Sep 2010 03:32:53 +0000

This command will help you to find the files created one day before in the specified folder.

find . -type f -mtime 1 -exec ls -lth ‘{}’ \;

ORA-1578: ORACLE data block corrupted

aarthimudhalvan — Fri, 27 Aug 2010 06:06:33 +0000

Issue:

Database is in Flashback Mode.

Enabled No logging on some db Tables

Recover the database.

Truncate those no logging Temporary tables.

Now we get error message ORA-1578: ORACLE data block corrupted

Reason:

Oracle says it is a behavior in 10g and fixed in 11g Rel1.

Cannot Reuse a Corrupt Block in Flashback Mode, ORA-1578 [ID 729433.1]

In 11g (11.1 releases) there is an optimization introduced to skip the block read if the object was dropped before the flashback retention range, and this will help with corrupt blocks on disk.

Flashback Database disabled automatically

aarthimudhalvan — Fri, 27 Aug 2010 06:04:33 +0000

Issue 1:

Intially Flashback Database was enabled but noticed Flashback was disabled automatically long time ago.

Reason:

It could be because the flashback area 100%

Once Flashback Area become 100% full then oracle will log in Alert that Flashback will be disabled and it will automatically turn off Flash Back without user intervention.

How can I check if there is anything rolling back?

aarthimudhalvan — Wed, 28 Jul 2010 03:22:47 +0000

It depends on how you killed the process.

If you did and alter system kill session you should be able to look at the used_ublk block in v$transaciton to get an estimate for the rollback being done.

If you killed to server process in the OS and pmon is recovering the transaction you can look at V$FAST_START_TRANSACTIONS view to get the estimate

Explain the relationship among database, tablespace, and datafile.

aarthimudhalvan — Thu, 01 Jul 2010 02:34:36 +0000

The database is logically divided into one or more tablespaces.
For each tablespace we explicitly create one or more datafiles.

How to recover if we delete a data file at OS level no backup for that?

aarthimudhalvan — Mon, 28 Jun 2010 02:55:37 +0000

bring the database to the mount state
sql>alter database create datafile ;
sql>recover datafile ;
sql>alter database open;

How do you see how many instances are running?

aarthimudhalvan — Tue, 22 Jun 2010 10:26:58 +0000

In Linux, Unix the command: ps -ef|grep pmon
In Windows: services.msc

Which is more efficient Incremental Backups using RMAN or Incremental Export?

aarthimudhalvan — Mon, 21 Jun 2010 09:48:00 +0000

RMAN

You lost some datafiles and you don’t have any full backup and the database was running in NOARCHIVELOG mode. What you can do now?

aarthimudhalvan — Fri, 18 Jun 2010 06:04:48 +0000

You have lost datafiles and you dont have backup and database is not running in archive log mode……
So we need to recreate the datafiles which will be empty….. you can not recover, becuase you dont have backup and database not in archive log mode

You loss one datafile and DB is running in ARCHIVELOG mode. You have full database backup of 1 week old and partial backup of this datafile which is just 1 day old. From which backup should you restore this file?

aarthimudhalvan — Thu, 17 Jun 2010 05:45:44 +0000

Restore it from Full backup and recover that data file using archive log files which are after Full backup to till date