Recently I discovered in a legacy Oracle 8.1.7.3.0 database that the tablespace holding de AUD$ table has been in backup mode for six months. Dunno who issued the begin backup command on it six moths ago.
- The scheduled backups are cold backups that will not issue a end backup command on any tablespace. The database can be shutdown and started up with no problemo.
- The datafiles belonging to the AUD$ tables have a modification date of just right now.
- When you query the AUD$ table you can see that it's being updated almost every minute. This table is inserted data continously.
- I understand that REDO information is generated when a datafile is in active backup mode but that tablespace has been un backup mode for six months for Pete's sake.
My questions:
- Can this tablespace cotinue in active backup mode forever with no consequences?
- Is there a risk of losing data?
- Is this a disaster waiting to happen?
- What exactly is happening here?
Best Answer
When we put the tablespace in backup mode Oracle copies whole changed data blocks into the redo stream in order to make the backup safe from fractured block. Copying whole data block instead of only the change may degrade the performance. Oracle strongly recommends to put the tablespace in backup mode only when required.
What Happens When A Tablespace/Database Is Kept In Begin Backup Mode (Doc ID 469950.1) (MOS Account needed)
The following is the excerpt from the Oracle Documentation.
Making User-Managed Backups of Online Tablespaces and Data Files