Lost Online Redo, checkpoints
- From: "Laimutis Nedzinskas" <Laimutis.Nedzinskas@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 10 May 2007 14:34:05 -0000
I have a question about write ahead protocol of Oracle.
If the *current* redo log is lost then
- Will Oracle halt? I think yes.
What happens if checkpoint crashes in the middle and the corresponding redo
logs(those containing changes for checkpoint) are lost. As far as I understand
the database could not be recovered without restore from backup.
Those statements are kind of supported by Oracle docs at
http://download-east.oracle.com/docs/cd/B19306_01/backup.102/b14191/recoscen008.htm#sthref1872
Except that at some point in this doc Oracle states that:
...
If the group is Current - Attempt to clear the log; if impossible, then you
must restore a backup and perform incomplete recovery up to the most recent
available redo log.
...
But bellow Oracle states that:
... The current log is the one LGWR is currently writing to. If a LGWR I/O
fails, then LGWR terminates and the instance crashes ...
(which is supported by my practical experience)
Isn´t this a contradiction?
Fyrirvari/Disclaimer
http://www.landsbanki.is/disclaimer
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