SAP MAXDB backup problem

[Former Member]

Hello All,

I have a question regarding MAXDB backup.

Our configuration of MaxDB is: all Maxdb executables are on disk d: and all data files are on disk e:.

We created the following backup templates:

dbmcli.exe -d CSD -u superdba,<PASSWORD> -uUTL -c medium_put CSD_DATA E:\sapdb\BACKUP\CSD\DATA\DAT0001 FILE DATA

(for full online backup)

dbmcli.exe -d CSD -u superdba,<PASSWORD> -uUTL -c medium_put CSD_LOG E:\sapdb\BACKUP\CSD\LOG\LOG0001 FILE LOG

(for log backups)

We also backed up our database with the following commands:

dbmcli.exe -d CSD -u superdba,<PASSWORD> -uUTL -c backup_start CSD_DATA

dbmcli.exe -d CSD -u superdba,<PASSWORD> -uUTL -c backup_start CSD_LOG

The operation was successful. 

Now we want to simulate data loss and recovery operation. We deleted all data/log files on disk e: (just to simulate the loss of the disk).

During the recovery process the transition to state "ADMIN" is successful. But when i click the button "NEXT" i have the following error:

Command 'db_restartinfo' has ended and failed with return code -24988.

                          4944 ERR     -24988 DBMSrv   ERR_SQL: SQL error

                          4944 ERR     -24778 DBMSrv   -902,I/O error

Can You kindly point me to right recover process? Should I restore my data-files from cold backup before recover database from online full backup?

Thanks

[yashwanthkumar_kethineed · Accepted solution]

Hello Aleksey,

Since you deleted the Log Volumes and data volumes, the the database is no longer restartable. The recovery process is trying to check if the database is restartable using the "db_restartinfo" command.

With this command it can determine the restart information of the database and also which data pages are in the log area and whether a restart of the database is possible. You need this information, during the normal recovery to make sure the database can be restarted to a consistent state.

If you are trying to simulate a disk loss/ disk failure situation, In this case you need to perform the recovery process with initialization. So what is "RECOVERY WITH INITIALIZATION" ??

It will initialize the data and log volumes of the current database, and import the data backed up in a complete data backup into the database.

This is also used to create a copy of a database, such as is required for the creation of a standby database.

Refer to http://maxdb.sap.com/doc/7_8/44/ed5673c85b67d6e10000000a155369/content.htm

Also refer to this WIKI page for more information about RECOVERY process.

http://wiki.sdn.sap.com/wiki/display/MaxDB/HowTo+-+SAP+MaxDB+recovery+with+Database+Manager+CLI

Let me know if you have any quesitons.

Regards,

Yashwanth

[Former Member · Accepted solution]

Hello Kumar,

thank You very much for quick response and clear explanation.

I just want to ask some additional questions.

I it possible to use MaxDB database for production activity after it was reinitialized from backup? Will it have the same system tables,users, amount of data-files, amount of log files? Is reinitialization of database from backup the only possible way to restore database after loss of all data-files/disks (except restore from off-line file-system backup)? Should I include off-line file-system backup into my backup strategy or on-line full backup plus logs backup will be enough to restore my database?

Thank You very much.

[yashwanthkumar_kethineed · Accepted solution]

Hello Aleksey,

There are several possibilities to approach your goal.

Refer to SAP Note: 952783 - FAQ: MaxDB high availability

It has a nice comparison of the different possibilities.

Answering your questions:

It really depends on the situation. How bad the disaster was. If you are an SAP Customer, you can always get help from the MaxDB experts to minimize the data loss in this situations as much as possible.

But yes if a complete disk failure is the case, then recovery with initialization is the only way. Unless you have other disaster recovery plans like (snapshots/splitmirror, file-system backup, cluster environment, shadown/standby database setup etc...)

Note that with "Recovery with initialization" you can bring the database back to the consistent state when the backup was taken. You will have all the system tables, users and data-files consistent at as they were at the time of backup. The log-area will be cleared and re-initialized.

Refer to the Wiki : http://wiki.sdn.sap.com/wiki/display/MaxDB/HowTo+-+SAP+MaxDB+recovery+with+Database+Manager+CLI

"Initialization means that all data are deleted and therefore lost forever. This includes the current log information on the log area as all volumes (data and log) are formatted. Furthermore the user names and passwords are overwritten with the corresponding data from the backup (except the data of the first database operator user). So it is necessary to know the user names and passwords contained in the backup. After the restore of the backup it is required to load the system tables. So this command is useful to create a copy of a database instance based on a data backup."

If there is a time gap between the "complete data backup" and the disk failure situation, chances of losing the data changes (stored in log area) in this time gap is possible. But we can still minimized the data loss in this time gap if you have consistent log backups taken at specific time intervals or you can use the automatic log backup feature of SAP MaxDB which automatically takes the log backups whenever the log area is full.

So when you recover a database instance with initialization, you import backups and recover the database status that they contain. To do so, you first import a complete data backup, followed by the related log backups.

Refer to SAP MaxDB Documentation for more detailed information about different tools available, data volumes and log volumes

http://maxdb.sap.com/documentation/

I hope this information helps you choose you disaster recovery plan for your production environment.

Regards,

Yashwanth

[Former Member · Accepted solution]

Hi all,

My SAP server was not opening means after starting from SAP Management Console it went to yellow state and then i read in blogs that LOG file is fulled thats why its not working make another one log file using MAXDB DBM after taking database back but how could i do this its size is 300GB, i couldnot make backup and log file got deleted. now what to do please help.

Please HELP...!

[Former Member · Accepted solution]

Hello,

if the first log file takes all disk space (300 GB) you can add another one on another disk.

If the first log file is deleted you can restore it from backup (if it possible).

If restore is not possible and you had a clean shutdown than, from my point of view, you can try to create a new log file with the help of button "New..." in the log file section.

Make a cold file system backup, before any actions performed over production system.