If you have a very large number of SQL databases (50+) on a single machine, you may encounter a variety of VSS and system errors. Some of these include:
- "Cannot create worker thread."
- "AddLegacyDriverFiles: Unable to back up image of binary Microsoft Link-Layer Discovery Protocol."
- "BACKUP DATABASE is terminating abnormally."
If the machine is running a 64-bit Windows OS, you can resolve this by increasing the max worker threads to twice the number of databases (e.g. if you have 200 databases, set the max to 400 threads). Then schedule a reboot of the server and try the backup again.
To do this using SQL Server Management Studio:
- In Object Explorer, right-click a server and select Properties.
- Click the Processors node.
- In the Max worker threads field, type or select the appropriate number as explained above.
Note: This may significantly increase CPU and RAM usage at the time of the snapshot.