maxdb log writer

[Former Member]

Quick question guys on an issue thats been bugging me.

I see logs such as these in dbm.prt and knlmsg files

Command 'util_execute suspend logwriter' is being executed.

Command 'util_execute resume logwriter' is being executed.

I normally see both the above in tandom.

However sometimes i only see the suspend command and there is no subsequent resume.      Our SAP hangs as none of the processes can connect to db due to all the user tasks in "LogIOwait" status.    We remain in this hung state for a couple of hours.

Then again I see another attempt for suspend log writing however this fails as log writer is already in suspended mode......

Then there is resume log writer command which succeds and all user tasks in maxdb are back to normal and so is SAP work processes.

This is the final leg of the dbm.prt log just before it gets fixed automatically.

2013-06-28 12:05:01       9212 INF        283 DBMSrv   Command 'util_execute suspend logwriter' is being executed.

2013-06-28 12:05:01       9212 ERR     -24580 DBMSrv   ERR_COMMAND_FAILED: Command 'util_execute' has ended and failed with return code -24988.

                          9212 ERR     -24988 DBMSrv   ERR_SQL: SQL error

                          9212 ERR     -24778 DBMSrv   -104,DBM command impossible at this time

2013-06-28 12:05:01       9212 INF          2 DBMSrvCo A DBM Server client connection was released (client process has process ID 9210 on computer mucua102qpi.muc.lantiq.com).

2013-06-28 12:05:13       9371 INF          1 DBMSrvCo A DBM Server client connection was established at 2013-06-28 12:05:04 (client process has process ID 9369 on computer mucua102qpi.muc.lantiq.com).

2013-06-28 12:05:13       9371 INF        283 DBMSrv   Command 'util_execute resume logwriter' is being executed.

2013-06-28 12:05:13       9371 INF        419 DBMSrv   Command 'util_execute' has ended with return code 0.

I am a novice with maxdb...can any one point me in the right direction here. I have already logged a call however SAP support are taking their good time so i thought i'd set it here to get the ball rolling.

Regards

Kalyan

[former_member188883]

Hi Kalyan,

Please refer SAP Note 869267 - FAQ: SAP MaxDB log area

Question (30)

To be able to support external snapshots at operation system level in the ONLINE operational state of the database, there must be an option to stop log writing for the duration of a snapshot and to allow log writing again after the snapshot has been created.

              Therefore, the providers of this external snapshot technology use the commands "suspend logwriter" and "resume logwriter".  These commands ensure that all volumes of a database configuration are consistent with each other.

   After the time of the "suspend logwriter", log writing is no longer possible. Change transactions must wait until log writing is allowed again using the command "resume logwriter".

These commands are logged both in the log dbm.prt and the log KnlMsg.

Hope this helps.

Regards,

Deepak Kori

[Former Member]

Hi Deepak,

Thanks for responding.

I have checked this already and as it seems that is only happening on certain occasions/days whereas we have a daily backup using snapshots. Either way it seems to me that the problem is either with maxdb or the way the snapshots are being taken. I will follow this through with SAP and see if we will get anywhere with this. thank you.

Regards

Kalyan