A database restore from a backup is a repair / recovery feature and not a high availability feature. If you are running a mission-critical system and if your database requires high availability, then please look into various H/A features available with SQL Server 2005.

If you are running a mission-critical system then you need your database to be available continuously or for extended periods of time with minimal down-time for maintenance tasks. So, the time required for databases to be restored must be kept as short as possible. Also, if your databases are large (VLDB's) , which may require a longer time to perform backup and restore then you SHOULD look into some cool features SQL Server offers to increase the speed of backup and restore operations to minimize the effect on users during both operations.

•   If you are backing up or restoring a Large Database (VLDB) then try and use multiple backup devices simultaneously to allow backups to be written to all the devices at the same time. (Note: A database can be restored from multiple devices at the same time)

•  Use a mirrored media set. A total of four mirrors is possible per media set. With the mirrored media set, the backup operation writes to multiple groups of backup devices. Each group of backup devices makes up a single mirror in the mirrored media set. Every mirror must use the same quantity and type of physical backup devices, which must all have the same properties.

• If the database recovery model is set to FULL, then use the available backup options e.x. (FULL, DIFFERENTIAL, LOG). This will help to minimize the number of backups that need to be applied to bring the database to the point of failure.

• Make use of the file and filegroup backup option . This allows for only those files that contain the relevant data, instead of the whole database, to be backed up or restored.

• Use Snapshot backups to minimize backup and restore time. (such type of backups are usually supported by third-party vendors)