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Online redo log in flashback area: best practise? [message #404422] Thu, 21 May 2009 14:55 Go to next message
Joppybt
Messages: 7
Registered: May 2009
Junior Member
When I do a default installation of Oracle XE on Linux (for example Ubuntu), two online redo log's are created in the folder /usr/lib/oracle/xe/app/oracle/flash_recovery_area/XE/onlinelog
If a default installation of Oracle does this, Oracle probably considers this an appropriate location for the files.

However: RMAN Documentation says:
Quote:
The flash recovery area should be on a separate disk from the database area, where active database files such as datafiles, control files, and online redo logs are stored. Keeping the flash recovery area on the same disk as the database area exposes you to loss of both your live database files and backups in the event of a media failure.

This suggest the online redo log's should not be stored in the flash recovery area.

Finally, a default 10.2.0.3 Standard Edition installation on Windows creates a folder c:\oracle\product\10.2.0\flash_recovery_area\ORCL\ONLINELOG put actually places the redo logs next to the DBF files. This is confusing.

Of course the best solution is to multiplex the redo logs to different locations but apart from that: what is the safest solution: redo logs with the database or in the flashback area.

Extra note: I configured RMAN for backups to the flashback area and the complete flashback area is backupped to another computer every night.

[Updated on: Thu, 21 May 2009 14:56]

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Re: Online redo log in flashback area: best practise? [message #404423 is a reply to message #404422] Thu, 21 May 2009 14:58 Go to previous messageGo to next message
Michel Cadot
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Registered: March 2007
Location: Nanterre, France, http://...
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The best is to put the online redo logs on their disks that are different of other ones and have 2 or 3 members per group.

Regards
Michel
Re: Online redo log in flashback area: best practise? [message #404752 is a reply to message #404422] Sat, 23 May 2009 04:55 Go to previous messageGo to next message
Joppybt
Messages: 7
Registered: May 2009
Junior Member
That leaves me wondering: why does the documentation tell you not to put the REDO log's in the flashback area while a default installation does put them there?
Re: Online redo log in flashback area: best practise? [message #404771 is a reply to message #404752] Sat, 23 May 2009 09:53 Go to previous messageGo to next message
Michel Cadot
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Those that make the documentation are not those that make the default installation (which by the way does not know any of you disk configuration and have to arbitrary choose from what it knows) are not those that produce best pratices...

Regards
Michel
Re: Online redo log in flashback area: best practise? [message #404791 is a reply to message #404422] Sat, 23 May 2009 19:57 Go to previous message
BlackSwan
Messages: 25046
Registered: January 2009
Location: SoCal
Senior Member
>while a default installation does put them there?
To keep the installation simple because it only knows about 1 volume/mount point.
Therefore all files must reside below it.
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