SCSI hard drives which are used in servers very often crash after a power down. The reason for this is that during long operation the hard drives acquire a fine build up from abrasion. This fine dust settles between the read/write head and the storage medium (drive plate) when the hard drive shuts off.

If a drive is then turned off for a longer period of time for maintenance for example, this could lead to "head sticking". Here the head actually sticks fast to to the surface of the storage medium.

Then, when the drive is put into operation again, the head can be torn off. In some cases, the heads don't rip off but become angled when the drive plate starts spinning which then leads to light surface damage. Each time the drive is initialized during operation, the damage increases ... until it leads to an actual head crash.

Prevention against this "drive coronary" includes the use of high quality drives and a regular total power down every 2-4 weeks. By regularly powering down, the dust "parkzones" are cleaned. Please note however, that before you turn the system off you make a complete data back up. 60% of all hard drive defects appear after a controlled or uncontrolled shut down !