Oracle Retention Policy

I am confused with the Oracle Retention Policy,
it said If you are not using a recovery catalog, then you should keep the recovery window time period less than or equal to the value of the control file parameter CONTROL_FILE_RECORD_TIME to prevent the record of older backups from being overwritten in the control file. If you are using a recovery catalog, then make sure CONTROL_FILE_RECORD_KEEP_TIME is greater than the time period between catalog resynchronizations.

I have got no idea what CONTROL_FILE_RECORD_KEEP_TIME can affect recovery window.
And how CONTROL_FILE_RECORD_KEEP_TIME can affect recovery catalog resynchronization.

Hope someone can help. Thanks!
mawinghoAsked:
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slightwv (䄆 Netminder) Commented:
The docs explain the individual parameters in detail.  What is confusing to you?

http://download.oracle.com/docs/cd/E11882_01/server.112/e17110/initparams034.htm#REFRN10020

CONTROL_FILE_RECORD_KEEP_TIME specifies the minimum number of days before a reusable record in the control file can be reused.


the post you gave explains the possible issue " to prevent the record of older backups from being overwritten in the control file."
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mawinghoAuthor Commented:
but recovery window time period can be set using
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS
then recovery window is set, then what is the purpose of CONTROL_FILE_RECORD_KEEP_TIME ?
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slightwv (䄆 Netminder) Commented:
CONTROL_FILE_RECORD_KEEP_TIME is specific to the control file itself independent of RMAN.

It just happens RMAN can also use the controlfile for what it needs.

That note is just saying you need to be aware of the independent parameter that might interfere with your backups.
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mawinghoAuthor Commented:
thanks for your reply.
sorry, I am new to the RMAN.

just one more question, then why If you are using a recovery catalog, make sure CONTROL_FILE_RECORD_KEEP_TIME is greater than the time period between catalog resynchronizations?

I read the document...but
"This parameter applies only to records in the control file that are circularly reusable (such as archive log records and various backup records). "

why the archive log records and various backup records are circularly resuable......
so confused...
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slightwv (䄆 Netminder) Commented:
I'm far from an RMAN expert myself.  I think the important term in that phrase is "resynchronizations".

If for some reason the catalog cannot be updated for a period of time, you need to make sure the data is preserved until it can be.

>>why the archive log records and various backup records are circularly resuable

redo logs are written to from top to bottom.  When full, Oracle moves to the next one and archives the one it just filled.  It will eventually move back to the original and start overwriting the 'old' info'.  This cycle goes on and on forever.

Thus, it's a circular file.
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mawinghoAuthor Commented:
thank you so much
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