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The second concern is that Time Machine is not an instantaneous fail-safe for data. Raid Arrays would still take precedence in data protection as they provide instant backup for data. Leopard takes hourly snapshots of the harddrive while Time Machine is running and then compiles them into a day-long image at the end of each day. For this reason it is important that users understand how to force a backup (CTRL Click time machine Icon) when working with sensitive data.
Comprehensive guide on using and troubleshooting Time Machine
Here is very helpful guide on Time Machine.