FULLTEXT catalogs and BACKUP - behaviour in SQL Server 2005
There should be no special consideration to perform BACKUP activities within your SQL Server environment. But if you are using FTS with full-text indexes/catalogs then you should be concerned about point-in time recoverability with the backups. You may be aware that from SQL Server 2005 onwardsyou can use the BACKUP and RESTORE statements to back up and restore full-text catalogs in the same way you back up and restore database file data, as the each full-text catalog is treated as a file and is included in the database file set that is backed up.
The backup operation will suspend the FTS engine to perform any sort of operations and flushes the all pending changes to the full-text catalog. AT the same the write process on catalogs will be stopped, thus these will be queued for further processing. Due to this behaviour you might see immediate performance hit on SQL Server and most of the times you may be stumbled to see this is due to backup operations.
BOL refers more more information about backing up database data, see Creating Full and Differential Backups of a SQL Server Database. After the full-text catalogs are backed up, SQL Server starts the MSFTESQL service, commits the updates queued in the notification log, and resumes regular operations. Be aware that during the backup process, full-text catalogs may not be dropped or added.