liveCache sync mechanism with data files

[Detelin_Nedev]

Dear all,

We have SCM system since years. However, during recent discussion we realized that the mechanism for data saving from caches to data files on the disk is not very clear.

Could you please advise how the data from are stored on the disk? Is this periodically or it is permanently, asynchronous or any other way...?

Or it is one time during the system shutdown, but it seems to be not is not very logical because if there is a system hang up - the data will be lost.

Thank you in advance for your suggestions.

Best regards,

Detelin Nedev

[Detelin_Nedev]

Thank you Natalia, James,

I will check the documentation you advised. I think now it is much clear the mechanism.

Thank you once again.

Best regards,

Detelin

[former_member229109]

Hello,

1.

During a savepoint, the database system writes the data that was changed since the last savepoint from the data cache (working memory) to the data area (permanent storage). The data written during a savepoint always represents a consistent state of the database.

Please review the details in the document at

Savepoint - Concepts of the Database System - SAP Library

2.

Review the information in the SAP note

869267 - FAQ: SAP MaxDB Log area

Pay attention to the answers on the questions 27. and 28.

Note, that if you deactivate the log, the system no longer writes implicit savepoints during routine operation. Therefore, changes to data are not written to the disk. If you do not stop the database with a correct shutdown, all data changes are irretrievably lost.

Regards, Natalia Khlopina

[JamesZ]

Hi Detelin,

LiveCache is a type of maxdb.
The database will automatically have savepoint and checkpoint will flush data from cache to disk.

Below facts will trigger savepoint :

1. time controlled, by default, savepoint is started every 10 minutes

2. data backup first starts a savepoint

3. when database was shut down
etc.

For the details, please refer to our maxdb expert session 10:

SAP MaxDB: The SAP Database - Training

The videos are very worthy to watch.

Best regards,
James