HANA restore delta without log backups

[wlourens2]

Dear Experts,

I have a client running Full HANA database backups on their DEV&QAS systems over weekends and Delta backups nightly.  Log mode is set to Overwrite.

DEV need to be restored to last night (Monday Night)

HANA catalog is available.  However, After selecting the full backup in "Restore Database" operation, the Delta backup is not available for selection.

I notice following from internet:

I restored database, and selected "restore database to latest point in time":

This worked.   Database was successfully restored to last night - restore used the Delta backup!

Confirmed, as table E070 contains all transports created until last night.

backup.log file of restore attached.

Is the HANA documentation incorrect, as I was able to restore to the last Delta backup?

Log backups use lots of space, but seems it is best to enable log backups also for DEV and QAS systems, as a Delta backup restore without log backups might be problematic?

Your feedback will be appreciated.

Kind Regards,

[mamartins]

You are mixing concepts regarding INCREMENTAL and DIFFERENTIAL backups. According to your image, you have scheduled daily INCREMENTAL backups, meaning that to restore FRIDAY backup you will need 6 backups: the latest SATURDAY FULL and all INCREMENTALS. If you scheduled DIFFERENTIAL, only 2 will be needed.

SAP HANA backup help is here: https://help.sap.com/docs/SAP_HANA_PLATFORM/6b94445c94ae495c83a19646e7c3fd56/c4663eabbb571014923a90c...

Incremental backup saves the data changed since the last data backup while differential backups save all the data changed since the last full data backup. Delta backups enable you to optimize your backup strategy, for example by less frequently executing the more time-consuming full data backups. Compared to log backups, delta backups can reduce the time needed for a recovery as the amount of log that needs to be replayed is reduced.

Log backups can bring the database to a more recent point-in-time, to recover the changes made since the latest data backup recovered. 

[wlourens2]

Dear mamartins,

Thank you for your valuable contribution.

Note taken that log backups can bring the database forward to a more recent point-in-time after the full/incremental/differential backup restore, but is not required.

From Recover documentation for HANA database on https://help.sap.com/docs/SAP_HANA_PLATFORM/f157e7b47b2a417a99eadd4b6c433b77/6be243b25bfa483ca325c9a...:

Prerequisites to restore:
A data backup or a data snapshot.
Delta backups and/or log backups
The log area

This means log backups are not required for a incremental restore. (only for a point-in-time restore)

I put my DEV/QAS databases in overwrite mode so not to deal with excessive logs, as point-in-time recovery is not needed; but it might be needed to restore to a specific day.

Strange that the HANA studio restore screens does still not provide a easy interface to restore to a certain incremental backup performed on a certain day.  This make recovey situations complex when this backup strategy is enabled.

I see another blog where a "trick" is required to restore to a certain delta backup => https://community.sap.com/t5/technology-blogs-by-sap/hana-database-recovery-trick-to-restore-to-in-b.... 

Kind Regards,