Data dissappeared after restart!

[Former Member]

Hi experts

We have newly installed CRM 7.0 and BI 7.0 systems based ond NW EHP1 on windows 2008 and MAXDB 7.7.06.10. Sometimes after restart of server, some data (some user master records, some customizing data,... etc.) is dissappeared.

We could not do any spesific configuration after installation. We only changed REDO LOG MANAGEMENT to DEACTIVATED and increased data file numbers.

Is there anybody have any idea?

Best Regards...

Edited by: Hande Kýlçer on Jun 16, 2010 4:16 PM

[former_member229109 · Accepted solution]

Hello,

-> Please review the document u201CHow Databases Log Data Changesu201D at

http://maxdb.sap.com/doc/7_7/44/d8ebaedaba5705e10000000a1553f6/content.htm

and document u201CLog Areau201D at

http://maxdb.sap.com/doc/7_7/19/d2235b234b4339b07627c8a1f2bfab/content.htm

-> As you deactivated the REDO LOG, the system writes NO savepoints implicitly.

If the database crashes, data loss may occur.

We recommend, that the Logwriter must not be deactivated for production operation.

To accelerate the administration tasks during the upgrades and larger loading jobs the Logwriter could be deactivated.

You could switch off the Logwriter using the DBM command in ADMIN status::

util_execute SET LOG WRITER OFF.

Log backups are not possible after switching off the the Logwriter. Backup history is broken down and flagged with the abbreviation HISTLOST. The backup history is restarted when you switch on the Logwriter again with the DBM command in the ADMIN status::

util_execute SET LOG WRITER ON

create a complete data backup in ADMIN or ONLINE status after that.

Thank you and best regards, Natalia Khlopina

[Former Member · Accepted solution]

Hi experts

Thanks for all replies. I always set noarchivelog mode for oracle and simple recovery model for MSSQL on my test environment and i've never got problems like this. I have no maxdb experience. If i activate redo log management and set overwrite mode for logs on maxdb, will i have similar problem? What is differences between redo log management activation and overwrite mode for log area?

Best Regards...

[lbreddemann · Accepted solution]

> I always set noarchivelog mode for oracle and simple recovery model for MSSQL on my test environment and i've never got problems like this.

So what?

The equivalent action in MaxDB is to choose log mode "Overwrite" and not to disable log management altogether.

When you disable log-management in other DBMS you'll also lose data when you don't shut the database down correctly.

And be very clear about this: this data loss is the direct consequence of a forcefull db shutdown (db_stop, kill -9, etc.).

Any clean shutdown (db_offline) would have saved your data!

> I have no maxdb experience. If i activate redo log management and set overwrite mode for logs on maxdb, will i have similar problem? What is differences between redo log management activation and overwrite mode for log area?

You might want to read the blog I already referred you to.

Or the notes the other commentors mentioned.

Or the documentation....

regards,

Lars

[Former Member · Accepted solution]

Hi experts

All referred documents and recommendations ar very usefull for my problem.

Thanks a lot!

[Former Member]

Hello ,

"

REDO LOG MANAGEMENT to DEACTIVATED

"

please check SAP note 869267

"

26. Can I deactivate log writing?

...

"

there is potential risk of dataloss in case of DB crash (or other unexpected shutdown), I suggest you use

overwrite mode instead disabling logwriter.

Regards

Ivan

what is wrong with SDN forum today, I only see initial post , with no replys , after I submit my post I see other replys above ?!?

Edited by: Ivan Levrinc on Jun 16, 2010 7:46 PM

[lbreddemann]

> We only changed REDO LOG MANAGEMENT to DEACTIVATED and increased data file numbers.

> Is there anybody have any idea?

You only deactivated the only thing in the database that would guearantee that your data is going to be saved.

Checking the documentation about this feature first would have helped here!

See my (already old) blog [Questions to SAP-Support (MaxDB): "Data is gone after reboot - where the heck is it?"|http://www.sdn.sap.com/irj/scn/weblogs?blog=/pub/wlg/15412] [original link is broken] [original link is broken] [original link is broken]; on this!

So, have fun with re-installing the systems!

regards,

Lars

[markus_doehr2]

> We have newly installed CRM 7.0 and BI 7.0 systems based ond NW EHP1 on windows 2008 and MAXDB 7.7.06.10. Sometimes after restart of server, some data (some user master records, some customizing data,... etc.) is dissappeared.

Question: Do you shut down the database properly BEFORE you restart the server? If no, then the system will issue a "db_stop" instead of a "db_offline", no savepoint will be written and hence the data is no more there.

Markus