7 Replies Latest reply on Dec 18, 2018 4:07 PM by Dude!

RMAN behavior and finding parent backup (level0) of an incremental backup

2982849 Dec 13, 2018 5:27 AM

Hi all,

I have quite a simple backup strategy

1) fullbackup level 0 - Saturday

2) cumulative incremental level 1 - Any other days

3) Retention period - 1 month

Q1) How do I find/confirm the parent of an incremental level 1 backup ? (e.g. how do i confirm the parent backup of the inc backup done on Wednesday)

Q2) On Week3 Saturday, i encounter a disk space issue and my level 0 fullbackup fail partially (3 out of 4 backupset created, the 4th backupset failed).

On the next day, Sunday - when the next cumulative incremental backup run, how will RMAN/Oracle behave ?
Does it based the incremental backup using the 3 x level 0 backupsets that were created successfully yesterday; and for those datafiles in the 4th backupset (which failed yesterday), it will base the incremental backup on the previous week (Week2 Saturday) level 0 backup ?

Regards,

Noob

1. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

Dude! Dec 13, 2018 7:15 AM (in response to 2982849)

Keep in mind that the default for the control_file_record_keep_time init parameter is 7 days. If you use a RMAN retention period of 1 month, you need to adjust the value accordingly, e.g. 35 days. Otherwise you risk loosing RMAN information and your retention policy cannot work.

When RMAN does a level 1 backup and no previous level 0 backup is found, then RMAN will automatically perform a level 0 backup instead of a level 1 backup.
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2. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

top.gun Dec 13, 2018 10:15 AM (in response to 2982849)

1) This command tells you everything you need to know:
restore database preview summary until time 'sysdate';

2) RMAN will source anythng missing from the latest backup, from the previous backup.
So RMAN will recognise the 3 latest L0 backupsets, and the 4th that is missing will be sourced from the previous Saturday.
The cumulative L1 backup will be a mixture of blocks since last Saturday, and the previous Saturday.
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3. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

2982849 Dec 13, 2018 6:45 PM (in response to Dude!)

Hi Dude,

Thanks for your reply.
If i am using a RMAN catalog, do i still need to set the control_file_record_keep_time to more then 7 days ?

Regards,
Noob
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4. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

2982849 Dec 13, 2018 6:47 PM (in response to top.gun)

Hi TopGun,

Thanks for the wonderful command.
From the preview, i see that one of incremental backup is done really base on a previous Saturday L0 backup.

Thank you!
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5. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

Dude! Dec 13, 2018 6:58 PM (in response to 2982849)

yes.
https://docs.oracle.com/cd/B19306_01/backup.102/b14191/rcmcatdb.htm#CIHECBCG
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6. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

2982849 Dec 14, 2018 6:02 AM (in response to Dude!)

Hi Dude,

Thanks for your reply and the doc link. It mentioned ->
If you maintain a recovery catalog, then use the RMAN RESYNCCATALOG command often enough to ensure that control file records are propagated to the recovery catalog before they are reused.
Make sure that CONTROL_FILE_RECORD_KEEP_TIME is longer than the interval between backups or resynchronizations. Otherwise, control file records could be reused before they are propagated to the recovery catalog. An extra week is a safe margin in most circumstances.
I am doing backup daily, and i think when i connect to the rman catalog , it will auto sync the controlfile backup information to the catalog - right ?

If that's the case, why would i stlil need to extend the CONTROL_FILE_RECORD_KEEP_TIME ? (since everyday during backup, the backup information from contorlfile will be sync to the catalog)

Regards,
Noob
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7. Re: RMAN behavior and finding parent backup (level0) of an incremental backup

Dude! Dec 18, 2018 4:07 PM (in response to 2982849)

You must ensure that you resynchronize the recovery catalog with the control file records before these records are erased. For example, if the rman retention is 1 month, control_file_record_keep_time default, then if backup the database only every 2 weeks, information will be incomplete, regardless of the retention setting and using a catalog database.
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