HANA Data backup

[former_member646800]

Hi All,

I have some questions regarding Data backup,

• If we trigger the data backup, will it take backup from Persistence level or memory level or both ?

• If from memory or both, then how it works ?

Please clarify about this concept experts.

Kind Regards,

Puneeth H A

[bharathyp · Accepted solution]

Hi Puneet,

Short answer to your question is.

No, data in-memory is not backed up. What happens is that a savepoint is created (read more on savepoints). So, once the savepoint operation is executed and the data in the memory is written to the persistence layer (data disk) that is what will be backed up.

If there are activities still going on whilst the backup is running, which is usually ofcourse the case, then when you recover you need to choose time in point recovery which will still have some slight data loss, hence in production enviroments we have HA. So, your node 2 will have ZERO data loss, yes! even in-memory data. Just choose mem-sync when you setup HA. But, that is a whole different thing.

Please go thru the link provided by Deepak and question 11 will be what you are looking for.

Best Regards,

Bharath

[former_member646800 · Accepted solution]

Hi Bharath,

Thanks for the reply.

I got your point.So it will backed up only persistence data.

Once we trigger the backup, how this backup operations works ? Means, this persistence backup will happen through memory ? Or this persistence will backed up without memory help ?

We could see sometimes memory usage will be high when backup running.In memory level,will it perform any checks while backup is running and then its backup ?

Please clarify these.

Kind Regards,

Puneeth H A

[deepak-kalra]

Hi Puneeth H A,

I will be explaining couple of terms to answer your question

Savepoint: At savepoint SAP Hana database moves all data changes from memory to the data volumes and redo log entries are also written to the log volumes for all changes to hana persistent data. By default, savepoints are created every five minutes, including during a backup.

Data Volume: It contains the data from the last completed savepoint.
i.e. /usr/sap/<SID>/SYS/global/hdb/data

Log Volume: It contains all changes on the data volume since the last completed savepoint.
i.e. usr/sap/<SID>/SYS/global/hdb/log

When Hana backup is triggered it back's up data area or log area according to type of backup selected.
Types of Hana Backup:
1) Full Backup - A data backup includes all the data that is required to recover the database to a consistent state.

2) Delta backups -
incremental backups - The data only changed since the last full data backup or the last delta backup.
differential backups - The data changed since the last full data backup.

3) Redo log backups - SAP HANA log segments in the log area are backed up automatically.

Please also look at SAP note 1642148 - FAQ: SAP HANA Database Backup & Recovery

Note: https://launchpad.support.sap.com/#/notes/1642148

I hope it helps

Regards
Deepak

[former_member646800]

Thanks for the reply Deepak.

Could you please elaborate, once we triggered the backup,in back-end how backup operations works.

Puneeth H A

[deepak-kalra]

Hi puni_12
Please go through SAP HANA Administration Guide and I am sure it will help you.
You can also follow SAP HANA Academy & follow denys.kempen

SAP HANA Service (CF): Administration, Backup and Recovery
Link: https://www.youtube.com/watch?v=Mieej8AqFkw&list=PLkzo92owKnVyhAGmDP4OsoPIj15-FEHtH

SAP HANA Administration Guide
Link: https://help.sap.com/viewer/6b94445c94ae495c83a19646e7c3fd56/2.0.03/en-US/c4663eabbb571014923a90c70c...

Regards
Deepak

[former_member651738]

Please read the guides as mentioned.

And maybe follow some training HA100 HA200 and HA250 might get you up to speed.

And yes memory and cpu use show that a backup is running. Because the backup process is using memory and cpu. If you check the logging you can get more detail on what and how Hana is for example doing a backup to disk.

Regards,

J.F.Trip