A couple of weeks ago I was troubleshooting a performance problem with the variations feature in Microsoft Office SharePoint Server (MOSS) 2007 and I needed to copy the content database to another environment for further analysis and testing. An easy (an unobtrusive) way to "snapshot" a database and copy it to another environment is to create a backup with the COPY_ONLY option:

BACKUP DATABASE [WSS_Content]
TO DISK = N'H:\WSS_Content.bak'
WITH NOFORMAT, NOINIT
    , NAME = N'WSS_Content-Full Database Backup'
    , SKIP, NOREWIND, NOUNLOAD, STATS = 10
    , COPY_ONLY

From SQL Server 2005 Books Online:

Taking a backup normally changes the database, in turn affecting other backups and how they are restored. Sometimes, however, a backup must be taken for a special purpose that should not affect the overall backup and restore procedures for the database.

A data backup is normally a base backup for one or more differential backups taken after it. Microsoft SQL Server 2005 introduces support for creating copy-only backups, which do not affect the normal sequence of backups. Therefore, unlike other backups, a copy-only backup does not impact the overall backup and restore procedures for the database.

In other words, by using the COPY_ONLY option I avoided screwing up the scheduled differential backups on the database.

However, there are a couple of issues with this approach:

• You cannot specify the COPY_ONLY option through the UI in SQL Server Management Studio, but this is no big deal -- you can start by configuring most of the backup options using the UI, script the action to generate the corresponding SQL, and then add the COPY_ONLY option as shown above
• You cannot restore a backup created using the COPY_ONLY option through the UI in SQL Server Management Studio; in the Restore Database dialog, when you select the From device option and then specify the backup file previously created with the COPY_ONLY option, no backup sets are displayed

The second problem was puzzling to me. After specifying my backup file, when I attempted to change to the Options page, I encountered the following error:

You must select a restore source.

When I first encountered this problem, I thought I had a corrupt backup file. However, by once again reverting to SQL instead of the UI, I was able to verify the backup was, in fact, valid:

RESTORE FILELISTONLY
FROM DISK = N'E:\NotBackedUp\Temp\WSS_Content.bak'

To restore from a COPY_ONLY backup, use a command similar to the following:

RESTORE DATABASE [WSS_Content_TEST]
FROM DISK = N'E:\NotBackedUp\Temp\WSS_Content.bak'
WITH FILE = 1
    , MOVE N'WSS_Content'
        TO N'E:\Microsoft SQL Server\MSSQL.1\MSSQL\Data\WSS_Content_TEST.MDF'
    , MOVE N'WSS_Content_Log'
        TO N'L:\Microsoft SQL Server\MSSQL.1\MSSQL\Data\WSS_Content_TEST_Log.LDF'
    , NOUNLOAD, STATS = 10

Note that when copying a database from one environment to another, you often need to use the MOVE option to specify the new location for the data and log files (to account for different disk configurations and available disk space).