There are two basic ways to get this done depending on present budget:
1. Configure a second BES server (with the same SRP ID & Auth Keys) to connect to the same config database. Do not start the BES services because it will cause RIM to disconnect your service. This server could be used as a "warm" standby. If your main server goes down you can start this BES server and it's services, which will be already configured to use the same database.
If the sql database is "down or corrupted", then you can use the most recent backup and "attach" it to the sql server. The backup may or may not be in sync, depending on your backup frequency and how new users were added since your last backup. This option requires additional hardware.
2. This option requires you to purchase a second BES lic (different SRP ID & Auth Key) and configure a "hot" standby server for DR. this new server should use the same configuraton database for ease of user migration during primary server failure. This option is transparent to the users, most will not even notice the slight delay in mail redirection. The delay will take as long as it takes to select all the users (ctrl + select) and move them over to the new BES server. This option will also need new hardware.
Neither of the options requires a recradling of the devices.