Log shipping is a SQL Server feature that may be employed to enhance the overall availability of your installation. It uses a primary server, which contains the active database, a monitor, and one or more secondary servers. Under log shipping, copies of the transaction log are supplied to the secondary servers on an on-going basis to the secondary servers. This configuration allows each secondary server to be in a standby state in case the primary goes offline.

Many sites also use the secondary server to off-load certain activities from the primary to minimize its load. However, a backup must NOT be performed on a secondary (or standby) server. Databases must always be backed up on the primary server and restored on the primary server. This requirement is based on the Microsoft SQL Server restriction that is outlined in Microsoft knowledge base article 311115. If you try to perform a backup on the secondary server, the result cannot be predicted. However, you may see a message in the dbclient log similar to the following:

16:33:26 [1208,2348] <16> CODBCaccess::LogODBCerr: DBMS MSG - ODBC message. ODBC return 
code <-1>, SQL State <37000>, Message Text <[Microsoft][ODBC SQL Server Driver][SQL 
Server]Database 'Mumbo' is  in warm-standby state (set by executing RESTORE WITH 
STANDBY) and cannot be backed up until the entire load sequence is completed.>