Example: Online Restore of a Read-Only File (Simple Recovery Model)

This topic is relevant for SQL Server databases under the simple recovery model that contain a read-only filegroup. Under the simple recovery model, a read-only file can be restored online if a file backup exists that was taken since the file became read-only for the last time.

In this example, a database named adb contains three filegroups. Filegroup A is read/write, and filegroups B and C are read-only. Initially, all of the filegroups are online. A read-only file in filegroup B, b1, has to be restored. The database administrator can restore it by using a backup that was taken after the file became read-only. For the duration of the restore, filegroup B will be offline, but the remainder of the database will remain online.