Question Back up error

[BeanTee]

We have been using window task scheduler to run daily database backup all the while. However, we encounter some issues since yesterday. The back up keep running without end. It seems that stuck somewhere. Below is the database log:
[2013/12/20@15:30:03.855+0800] P-5392 T-4448 I BACKUP 30: (-----) Login by Prem Bkup.
[2013/12/20@15:30:06.969+0800] P-5392 T-4448 I BACKUP 30: (12850) Backup blocks will be written to c:\backup.
[2013/12/20@15:30:06.977+0800] P-5392 T-4448 I BACKUP 30: (1362) Full backup started.
[2013/12/20@15:30:06.985+0800] P-5392 T-4448 I BACKUP 30: (6686) 2557805 active blocks out of 3840005 blocks in d:\databse will be dumped.
[2013/12/20@15:30:06.985+0800] P-5392 T-4448 I BACKUP 30: (6688) 1024 BI blocks will be dumped.
[2013/12/20@15:30:06.987+0800] P-5392 T-4448 I BACKUP 30: (9285) Backup requires an estimated 9.8 GBytes of media.
[2013/12/20@15:30:06.988+0800] P-5392 T-4448 I BACKUP 30: (9286) Restore would require an estimated 2567121 db blocks using 2.4M of media.
[2013/12/20@15:30:07.539+0800] P-5392 T-4448 I BACKUP 30: (5459) Begin backup of Before Image file(s).
[2013/12/20@15:34:30.554+0800] P-5392 T-4448 I BACKUP 30: (5460) End backup of Before Image file(s).
[2013/12/20@15:34:31.131+0800] P-5392 T-4448 I BACKUP 30: (5461) Begin backup of Data file(s).

I logged in to promon and kill the user session then the below shown in the log file:
[2013/12/20@16:49:48.167+0800] P-5392 T-4448 I BACKUP 30: (5462) End backup of Data file(s).
[2013/12/20@16:49:48.169+0800] P-5392 T-4448 I BACKUP 30: (1726) Backup cancelled, disconnected by server.
[2013/12/20@16:49:48.169+0800] P-5392 T-4448 I BACKUP 30: (-----) drbackup: failed to release _Db lock, returned -6

And i notice that the backup file is generated as usual file size. I didn't try to restore the backup file to check whether the backup file is generated correctly. I run the probkup command manually to generate the backup file again.

In normal situation, the above log should end with the below statements:
(5462) End backup of Data file(s).
(13625) Wrote a total of 52114 backup blocks using 6.8 GBytes of media.
(1364) Full backup successfully completed.

From windows task scheduler, it is observed that the tasks is always on "running" mode.

Can anybody explain what is happening?

 

[gareth.roberts]

I have seen this occur when another process tries to access the backup file whilst you are backing up. For example a backup job that is pushing it out to tape or and anti virus scan.

 

[BeanTee]

Hi Rareth, thank you for your reply. i doubt there is any other process running at the same time. Actually, there are few databases backup running at different timing. All fail... i suspect something wrong with the tasks scheduler. We restarted the server over the weekend. Now everything seems back to normal. However, the root cause of the incident is still a question mark...