Backup SQL with AlwaysOnGroup Setup

Hi,

We're backing up SQL 2012 transaction log.

From the activity monitor, i can see that the backup completed successfully.

but the SQL admin said that the disk keep getting full due to the transaction log not being truncated after the backup.

He added that the SQL was configured with AlwaysOnGroup setup.

I look around and found out that AlwaysOnGroup is not yet supported(I'm using netbackup 7.6.0.4).

The backup is pointing to the availibility name.

Is this the reason why the log wasnt truncated after the backup?

Is there any trick to backup the Transaction log if this was caused by the AlwaysOnGroup setup?

Any help is highly appreciated.

Regards,

Aris