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backup database plus archivelog
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Message Score Author Date
Hi all from the documentation - issuing plus ar...... sze jie koh Jul 10, 2022, 20:20
Documentation does not say it is necessary, it i...... Score: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 Pts Michel Cadot Jul 10, 2022, 20:52
hi michel thanks for your reply and nice to sti...... sze jie koh Jul 11, 2022, 19:13
I like to simplify issues for production managem...... Score: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 Pts Michel Cadot Jul 11, 2022, 19:37
hi michel just to clarify - in your illustratio...... sze jie koh Jul 12, 2022, 18:00
Yes. Regards Michel ... Michel Cadot Jul 12, 2022, 20:14

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Subject: backup database plus archivelog
Author: sze jie koh, Singapore
Date: Jul 10, 2022, 20:20, 38 days ago
Os info: Solaris 11
Oracle info: 19c
Message: Hi all

from the documentation - issuing plus archivelog does the following


1) Run the ALTER SYSTEM ARCHIVE LOG CURRENT statement.
2) Run BACKUP ARCHIVELOG ALL.
3) Back up the rest of the files specified in the BACKUP command.
4) Run the ALTER SYSTEM ARCHIVE LOG CURRENT statement.
5) Back up any remaining archived logs generated during the backup.

The preceding steps guarantee that data file backups taken during the command are recoverable to a consistent state.


I am trying to understand if step 1 and 2 is necessary to ensure the backup are recoverable to consistent state ? if yes - why ?

if a database change is currently recorded in the ORL and the change data is not flush to disk yet - surely there will be a log switch during the backup of the database and the ORL will get archived and backup isn't it ?

in any case - step 4 will also do a log switch and archive the archivelogs

so why is step 1 and 2 necessary ?

Thank you
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Subject: Re: backup database plus archivelog
Author: Michel Cadot, France
Date: Jul 10, 2022, 20:52, 38 days ago
Score:   Score: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 Pts
Message:
Documentation does not say it is necessary, it is just safer and faster to then backup files (as dirty blocks are flushed onto disk).

Why not using a single command BACKUP DATABASE PLUS ARCHIVELOG and let Oracle choose what it has to do in the best way?

Regards
Michel
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Subject: Re: backup database plus archivelog
Author: sze jie koh, Singapore
Date: Jul 11, 2022, 19:13, 37 days ago
Message: hi michel

thanks for your reply and nice to still see you around

i hope to have your opinion the below

1) i need to have a 30min RPO so i am backing up the archivelog every 30 minutes
backup archivelog all delete input

2) everday at 1am - i am also doing monday full backup and cumulative backup on the rest of the days - the backup is run with plus archivelog delete input;
backup database plus archivelog delete input

i am afraid that 1) and 2) might run concurrently causing some archivelog to be deleted before it is backup thus i have removed the 'plus archivelog delete input' from the backup database command

it is currently just

backup archivelog all delete input -- every 30 mins

backup incremental level 0 database -- every sunday
backup incremental level 1 cumulative database -- monday to saturday


3) i do not have a large FRA area - so after backing up the archivelog i need them to be deleted

===========================================================

the purpose of doing backup database plus archivelog is so that i am able to restore the database to a consistent state using this 1 backup
but if i am backing up archivelog every 1/2 hour with delete input - it means that some of the archivelogs would have already been deleted while the backup database is running - this will defeat the purpose of backup database plus archivelog then ?

q1) do you think my current backup strategy is sound ? is it okay for me to remove the 'plus archivelog' from the backup database command ?

do i lose out anything other then losing the capbility to restore the database to a consistent state in 1 single backup
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Subject: Re: backup database plus archivelog
Author: Michel Cadot, France
Date: Jul 11, 2022, 19:37, 37 days ago
Score:   Score: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 PtsScore: 200 Pts
Message:
I like to simplify issues for production management.
So I advise you have only 1 job that starts every 30 minutes and if it is Sunday at, say, 0:00 then do a level 0 backup it, if it is Monday to Saturday same hour then do a level 1 backup otherwise do an archivelog backup.
If you think that a database backup can last more than 30 minutes and conflict with an archivelog backup then you can a) add a verification that a db backup is not currently running before doing an archivelog backup or b) modify the job to let it schedule itself its next execution instead of doing an external scheduler.

Regards
Michel
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Subject: Re: backup database plus archivelog
Author: sze jie koh, Singapore
Date: Jul 12, 2022, 18:00, 36 days ago
Message: hi michel

just to clarify - in your illustration earlier - will you still include plus archivelog in your backup database statement ?
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Subject: Re: backup database plus archivelog
Author: Michel Cadot, France
Date: Jul 12, 2022, 20:14, 36 days ago
Message:
Yes.

Regards
Michel
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