| Backup Strategy [message #51859] |
Tue, 18 June 2002 10:40  |
XG
Messages: 1
Registered: June 2002
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Junior Member |
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Hi,
In terms of database backup , does any experienced DBA can tell me in what kind of circumtances one should use logical backups with EXP/IMP, and when use cold backup to backup all the datafiles, control files, etc.?
Thanks.
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| Re: Backup Strategy [message #51860 is a reply to message #51859] |
Tue, 18 June 2002 11:21  |
Grant
Messages: 578
Registered: January 2002
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Senior Member |
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Backup strategy is a very big subject and should be reviewed every six months or when a significant change occurrs. The bottom line is that you need to be able to restore the database up the point of failure. You need to invest in a good backup/recovery book. Most backup strategies have to do with the size, time of recovery, and importance of the data.
Cold backup along with archiving turned on is a good startegy to recover to a point in time. How you do that will determine how fast you can recover. For example if you do a cold backup once a week and the DB files and archive logs are still on disk recover is fast. Provided the hardware failure isn't where those files reside, ouch!
Export/import is good for recovering a table or object that was deleted quickly without having to restore the entire database. I use export for ALL databases regardless. I also use export/import to refresh test or development DB's. I also export a DB BEFORE I make changes so I can put it back if I need to. Of course that depends on the size. I do schema exports frequently when I need to for various reasons.
I use hot backups using RMAN cause we can't take the DB down and it goes directly to tape. I only use RMAN for production databases.
One thing is don't fail to restore your DB when it fails or you may be out of a job. Do a lot of research on your options.
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| Re: Backup Strategy [message #51867 is a reply to message #51859] |
Tue, 18 June 2002 12:27 |
Trifon Anguelov
Messages: 514
Registered: June 2002
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Senior Member |
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Both strategies could be used only in non 24x7 environments.
Cold backup will guarantee you no data lost, in case you have all archived logs. Good for production environments with downtime backup window. However shutdown you will be flushing your buffer cache and library cache, which on startup will require "cache warmup"
Exp/imp for QA and Dev environments, with not so big data volumes. Good for restoring dropped tables or any objects, which developers usualy use as toys to play around... No downtime is required, but the restore is up to the last full db export.
Again it depends on your db size, down time windows, the db purpose, your willingness to take chances... :-)
Hope that helps,
clio_usa
OCP - DBA
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