Often times engineers make the fundamental mistake of choosing the wrong type of RAID when a server is setup. When disaster strikes this may leave them with data loss, long backup process, loss of time etc.
Its important to choose the right type of RAID when first setting up the server. Its important to identify what role the server is going to play, and then choose the appropriate RAID Level.
I came up with a chart which I think covers the type of RAID and what each one is best used for. Hope this helps.