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OracleApprender avatar image
OracleApprender asked

What are the advantages of operating a database in ARCHIVELOG mode over operating it in NO ARCHIVELOG mode ?

Can anybody let me know the difference between ARCHIEVELOG mode and NO ARCHIVELOG mode of database operations. Please let me know the differences. Thank you very much in advance.

oracleperformancelogs
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HillbillyToad avatar image
HillbillyToad answered

If you run in NOARCHIVELOG mode, if your database crashes, you can only recover to the point of time of your last backup.

ARCHIVELOGMODE allows you to recover to the point of the crash. Downside is it takes more diskspace and can cause the db to freeze if that disk fills up. If you have a production system with no tolerance for loss, this isn't an option.

If you're running a DW that does nightly loads, then you can get away with NOARCHIVELOG mode most likely.

Please go read the Oracle Certification docs on the Backup & Recovery process. Pay special attention to the RMAN section.

3 comments
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Thank you for your answer. I'll explore more as you suggested.
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No worries. Feel free to mark the question as answered with your vote :)
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OracleApprender avatar image
OracleApprender answered

Toad has answered this question. Answer is : If we run in NOARCHIVELOG mode, if the database crashes, we can only recover to the point of time of our last backup.

ARCHIVELOGMODE allows us to recover to the point of the crash. Downside is it takes more diskspace and can cause the db to freeze if that disk fills up. If we have a production system with no tolerance for loss, this isn't an option.

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So data loss on a production database is OK but keeping up with archived logs is not? All of our production databases are required to run in ArchiveLog mode. In addition we set up script to compress logs that are older than 1 hour and delete logs older than 1 week. Sizing additional disk partitions to hold archived logs is part of the database setup process. There are lot more things than just filling up an ArchivedLog disk that can stop your database in its tracks. I understand availability is an issue, but personally I think data protection and recoverability is more important.
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Yes..you are cent percent correct.
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Not running ARCHIVELOG MODE b/c you're afraid the db will seize when you run out of disk space is...well, it's interesting :) Make archiving your archive logs part of your regular maint cycle. No worries then :)
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dmann avatar image
dmann answered

I have used NOARCHIVELOG mode for some Dev Databases. Performance is a little better with NOARCHIVELOG as there is no overhead for writing the Archived Redo Logs to the Archive Log Destinations. (Keep in mind that ONLINE redo logs are always written to, no way around that).

That being said the customer was informed of and accepted the fact that they could only restore to the previous full backup. Since they were Development systems that could be rebuilt with scripts this was not an issue.

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Graham Oakes avatar image
Graham Oakes answered

Running in archivelog mode also enables you to run a dataguard standby that you can switch(or fail)over to as and when necessary.

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