This post covers how to utilize the new package DBMS_RA.CREATE_ARCHIVAL_BACKUP to dynamically create KEEP archival backups from a ZDLRA.
When using this package to schedule KEEP backups, I recommend creating restore points with every incremental backup. Read this blog post to find out why.
PROCEDURE CREATE_ARCHIVAL_BACKUP(
db_unique_name IN VARCHAR2,
from_tag IN VARCHAR2 DEFAULT NULL,
compression_algorithm IN VARCHAR2 DEFAULT NULL,
encryption_algorithm IN VARCHAR2 DEFAULT NULL,
restore_point IN VARCHAR2 DEFAULT NULL,
restore_until_scn IN VARCHAR2 DEFAULT NULL,
restore_until_time IN TIMESTAMP WITH TIME ZONE DEFAULT NULL,
attribute_set_name IN VARCHAR2,
format IN VARCHAR2 DEFAULT NULL,
autobackup_prefix IN VARCHAR2 DEFAULT NULL,
restore_tag IN VARCHAR2 DEFAULT NULL,
keep_until_time IN TIMESTAMP WITH TIME ZONE DEFAULT NULL,
max_redo_to_apply IN INTEGER DEFAULT 14 --> Added in 21.1 June PSU
comments IN VARCHAR2 DEFAULT NULL);
NOTE: This blog post was updated to include the MAX_REDO_TO_APPLY parameter which is not documented as of writing this post.
The documentation can be found here.
These archival KEEP backups can be sent to either
- TAPE - Using the copy-to-tape process you can send archival backups to physical tape, virtual tape, or any media manager that uses a "TAPE" backup type.
- CLOUD - Using the copy-to-cloud process you can send archival backups to an OCI object store bucket which can be either on a local ZFSSA (using the OCI API protocol), or to the Oracle Cloud directly.
How to use this package
1. Identify the Database
Because this is more of an on demand process, you have to execute the package for each database separately (rather than by using a protection policy), and identify for each database the point-in-time you want to use for recovery..
2. Set Archival Restore Point
Because the archival backup is dynamically created using existing backups the restore point works differently than if you create the KEEP backup on demand from the protected database.
When you create a KEEP backup from the protected database, the backup contains
- Full backup of all datafiles
- Backup of spfile and controlfile
- Backup of archive logs created during the backup starting with a log switch at the beginning of the backup.
- Final archive logs created by performing a log switch at the end of the backup.
When you create an Archival backup from the ZDLRA , the backup contains
- Most current virtual full backup of each datafile prior to the point in time for recovery that you choose.
- Backup of spfile and controlfile
- Backup of the active archive logs generated when the oldest virtual full datafile backup started, up to the archive logs needed to recover until the point in time chosen for recovery.
As you can see a normal KEEP backup generated by the protected database is a a "self-contained" backup that can be recovered only to the point in time that the backup completed. You can increase the recover point by adding additional KEEP archival log backups after the backup.
The dynamically created KEEP backup generated by the ZDLRA is also a "self-contained" backup that can be recovered to any point in time after the last datafile backup completed, but it also includes any point in time up to the restore point identified.
Choices for a dynamic restore point
There are 3 options to choose a specific restore point. If you do not set one of these options, the KEEP backup will be created using the current restore point of the database.
- RESTORE_POINT - If you set a unique restore point in the database immediately following an incremental backup (or at a later point in time), you can create a KEEP backup that will recover to that point-in-time. When using this process, after creating the restore point you should ensure that you also perform a log switch, and a log sweep to backup the archive logs. This restore point name is used as the default RESTORE_TAG, and should be unique. The recommended name (because it is the default KEEP restore tag) is "<KEEP_BACKUP_><yyyyMMddHH24miSS>". BUT- in order to better identify the restore point, I would use a shorter name that just contains the date (assuming you are only performing an single daily incremental backup), for example "KEEP_BACKUP_MMDDYY". By using a restore point, you can better control the amount of archive logs necessarily to recover the database.
- Incremental forever backups ensure that the duration of the backup is much shorter than a typical full KEEP backup limiting the amount of archive logs necessary to have a recovery point.
- Setting a restore point immediately following the backup ensures that the recovery window following the last datafile backup piece is short also limiting the amount of archive logs necessary.
- RESTORE_UNTIL_SCN or RESTORE_UNTIL_TIME - I am grouping these 2 choices together, because they are so similar. Unlike using a restore point that is preset, using either of these options will create the KEEP archive backup with a recover point as the SCN number given or the UNTIL TIME given (using the databases timezone).
FROM_TAG - The documentation states that only backups containing the FROM_TAG will be considered if a FROM_TAG is set. I am thinking this would make sense if you let the restore point default to the current time, and you want to choose which backup pieces to include. I am not sure of the full use of this option however.
WARNING: This process only looks back 14 days for a full backup to start the KEEP backupset with. If you do not have a full backup within the 14 day window this can be over ridden with the MAX_REDO_TO_APPLY parameter in the package call. This was added in the 21.1 June PSU to allow customers to set a window farther than 14 days.
RECOMMENDATIONS
- Because you can create up to 2048 RESTORE_POINTs in a database, and normal restore points are automatically dropped when necessary, I would recommend creating a restore point following each incremental backup with the format mentioned above, This will allow you to create a self-contained FULL KEEP backup from any incremental backup as needed. This can be used to easily create an end-of-month KEEP backup (for example).
- I would use the RESTORE_UNTIL options when it is necessary to create a KEEP backup as of a specific point-in-time regardless of when the backup completed. This would be used if the recovery point is critical.
WARNING
Before creating the archival backup, ensure you have the archive logs backed up that are needed to support the recover point, and ensure there is enough time for the incremental backups to virtualize. You many need perform a log switch and execute an additional log sweep prior to scheduling the archival backup.
3. Set Archival Options
COMPRESSION_ALGORITHM - The default is no compression, and if the backup piece is already compressed, it will not try to compress the backup again. The documentation does a good job of going through the options, and why you would chose one or the other. Keep in mind that if your database uses TDE for all the datafiles, there will be no gain with compression, and the extra resources required for compression may slow down the restore. Also, the compression is performed by the ZDLRA (RMAN compression), but the de-compression is performed by the protected database during restore.
ENCRYPTION_ALGORITHM - The default is no encryption, but it is important to understand that any copy-to-cloud processing MUST have encryption set. It is also important to understand that the ZDLRA must be using OKV (Oracle Key Vault) to store the encryption keys when encryption is set. The list of algorithms can be found in the documentation.
4. Set Archival Location and Name
ATTRIBUTE_SET_NAME - This must be specified, and this identifies the backup location to send the archival backups.
FORMAT - By default the backup pieces are given handles automatically generated by the ZDLRA, this setting allows you to change the default backup piece format using normal RMAN formatting options.
AUTOBACKUP_PREFIX - - By default the autobackup pieces will retain the original names, but you can add a prefix to the original autobackup names.
5. Set Restore TAG
By default the RESTORE_TAG defaults to "<KEEP_BACKUP_><yyyyMMddHH24miSS>". This can be overridden to give the backup a more meaningful tag. For example, the end-of-month backup could be tagged as "MONTHLY_12_2023", making it easier to automate finding specific KEEP backups.
RECOMMENDATIONS
I would set the Restore Tag to a set format that makes the KEEP backups easy to find. You can see the example above.
6. Set KEEP_UNTIL time
The default KEEP_UNTIL time is "FOREVER". In most cases you want to set an end date for the backup, allowing the ZDLRA to automatically remove the backup when it expires. This date-time is based on the timezone of the protected database.
SUMMARY
If using this functionality to dynamically create Archival KEEP backups...
- I would set a Restore Point in each database immediately following every incremental backup.
- I would schedule this procedure to create the archival backup with a formatted restore tag to make the backup easy to find.
- If backing up to a CLOUD location, I would use retention rules to ensure the backups are immutable until they expire.
