I always recommend my client to go with the latest and great version of tools like SQL Server Management Studio (SSMS). In this blog, we would learn about a situation where an older version of SSMS was giving an error while adding a new database to existing availability group – This BACKUP or RESTORE command is not supported on a database mirror or secondary replica.
THE SITUATION
My client had an existing availability group which was set up and deployed by a vendor. Now, they wanted to add a new database to an existing availability group. They were using the wizard to add the database. They selected the option to do a fresh backup/restore. Due to old SSMS version, automatic seeding option was not available. Here was the error which they were getting in the UI.
Here is the text of error message:
Restoring database log resulted in an error. (Microsoft.SqlServer.Management.HadrTasks)
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ADDITIONAL INFORMATION:
Restore failed for Server ‘SQLSERVER-1’. (Microsoft.SqlServer.SmoExtended)
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System.Data.SqlClient.SqlError: This BACKUP or RESTORE command is not supported on a database mirror or secondary replica. (Microsoft.SqlServer.Smo)
The surprising part was that even after the error came, the database was added to the availability group successfully. This means the error was a benign error and can be ignored but I want to know what error was appearing. To dig further I generated the script of Always On and executed it manually. It failed with the exact same error.
WORKAROUND/SOLUTION for RESTORE command
It was clear that the database was getting added successfully due to automatic seeding. We can see below in ERRORLOG.
Primary Replica:
• Database backed up. Database: OneMoreDatabase, creation date(time): 2019/06/11(13:21:51), pages dumped: 355, first LSN: 38:2800:1, last LSN: 38:2824:1, number of dump devices: 1, device information: (FILE=1, TYPE=DISK: {‘\\sqlserver-0\Share\OneMoreDatabase.bak’}). This is an informational message only. No user action is required.
• Database backed up. Database: OneMoreDatabase, creation date(time): 2019/06/11(13:21:51), pages dumped: 522, first LSN: 38:2712:1, last LSN: 38:2824:1, number of dump devices: 1, device information: (FILE=1, TYPE=VIRTUAL_DEVICE: {‘{3AFC5950-4E79-4225-B572-0A70AD876E45}’}). This is an informational message only. No user action is required.
• Log was backed up. Database: OneMoreDatabase, creation date(time): 2019/06/11(13:21:51), first LSN: 38:2712:1, last LSN: 38:2824:1, number of dump devices: 1, device information: (FILE=1, TYPE=DISK: {‘\\sqlserver-0\Share\OneMoreDatabase_20190626054651.trn’}). This is an informational message only. No user action is required.
Secondary Replica:
• Database was restored: Database: OneMoreDatabase, creation date(time): 2019/06/11(13:21:51), first LSN: 38:2712:1, last LSN: 38:2824:1, number of dump devices: 1, device information: (FILE=1, TYPE=VIRTUAL_DEVICE: {‘{E9D35CEB-D6FD-40D6-A73C-06560EFD95D9}’}). Informational message. No user action required.
• Database was restored: Database: OneMoreDatabase, creation date(time): 2019/06/11(13:21:51), first LSN: 38:2800:1, last LSN: 38:2824:1, number of dump devices: 1, device information: (FILE=1, TYPE=DISK: {‘\\sqlserver-0\Share\OneMoreDatabase.bak’}). Informational message. No user action required.
If we look at the backup and restore commands, there are two backups. Once on TYPE=DISK and another on TYPE=VIRTUAL_DEVICE. The second backup comes when there is an automatic seeding happening for the database.
Running script manually fails with below (on secondary). This is the same what we get from the UI.
Connecting to sqlserver-1…
Msg 3059, Level 16, State 2, Line 29
This BACKUP or RESTORE command is not supported on a database mirror or secondary replica.
Msg 3013, Level 16, State 1, Line 29
RESTORE LOG is terminating abnormally.
Disconnecting connection from sqlserver-1…
Connecting to sqlserver-1…
Msg 41145, Level 16, State 1, Line 67
Cannot join database ‘DWConfiguration’ to availability group ‘XAG’. The database has already joined the availability group. This is an informational message. No user action is required.
Disconnecting connection from sqlserver-1…
When I compared the script generated from SSMS for an old and new version, I found the difference which explained the issue clearly. This was the extra command in the new version of SSMS.
ALTER AVAILABILITY GROUP [XAG] MODIFY REPLICA ON N'sqlserver-1' WITH (SEEDING_MODE = MANUAL)
This means that SSMS is smart enough to change the mode to MANUAL when below option is selected.
So, to conclude, the seeding was set to AUTOMATIC for the replica. When we were using an older version of SSMS, it was doing both automatic seeding and backup/restore. This was causing restore to fail because it was seeded already and added successfully.
You can use below query to find replica seeding mode.
SELECT ag.name ,replica_server_name ,seeding_mode_desc FROM sys.availability_replicas ar ,sys.availability_groups ag WHERE ag.group_id = ar.group_id AND name = 'AGSQLAGDB'
Have you seen such errors of SSMS? Please comment and let me know.
Reference: Pinal Dave (https://blog.sqlauthority.com)
First appeared on SQL SERVER – Add Database to Availability Group Failure – This BACKUP or RESTORE Command is Not Supported on a Database Mirror or Secondary Replica