Oracle internals, debugging and undocumented features
Supported Backup, Restore and Recovery Operations using Third Party Snapshot Technologies
January 13, 2009Posted by on
I live in Florida and there are many hurricanes every year.. So disaster recovery is important topic for me.And there is constant battle between Unix/Linux team or Storage team ( Storage Farmers ) and DBA’s when comes to restoring and recovering.Some company split tasks.
Backup and restoring are part of a Unix/Linux team or farmers and recovery is stritcly done by DBA..
Personally I preffer to be in charge of both but sometime you do not have a choice…
I remember that many times during recovery we will run into issues related to fuzzy files .System admin folks took snapshot without placing database in BACKUP mode.And then finger pointing starts..
The main reasons why Oracle requires putting the associated data files or database in BACKUP mode are
ensuring file header consistency prior to the backup and updating the file headers with the recovery start time
creating sufficient redo to recover from any fractured or inconsistent blocks
creating a “end backup” marker to demarcate the minimum recovery time to ensure database consistency after restoring and recovering the data files.
But here is good news:
Oracle will officially support the following operations assuming that the third party snapshot technology can meet the prerequisites listed in the next 2 sections.
Full database snapshot without the database in backup mode
1 . If a point-in-time copy of the database is required, the snapshot must contain all the data files, control files and online redo logs.
2. If full (i.e. zero data loss) recovery or point-in-time recovery is required, the snapshot must contain only the data files or have the ability to restore only the data files.
For detail information refer to Metalink Note 604683.1