Sysadmins are divided into those who do not make backups and those who already do. folk wisdom
Today, the notorious forum sysadmins.su (forum of real professionals) happened grief. Flew RAID array and most of the data was lost. According to estimates, the guys rolled the forum as much as 2 months.
And sad and funny. ')
UPD: By the way, who is registered there, can read the relevant topic about it.