Is this a laptop? I guess it is. The firmware in your harddisk is parking it's head and you hear it click (or maybe it clicks when it is waking up). You can set the APM level for the disk with hdparm or smartctl try to get the current value like that # smartctl -g apm /dev/sda or with # hdparm -I /dev/sda it is probably at 128 or lower set it to a higher value 192 or even 254, this is hard disk vendor dependent, unfortunately. google for load cycle count and you will find plenty results. This seems to be a problem with a lot of disks.
Just to update, the hdparm command gives me: ... Capabilities: LBA, IORDY(can be disabled) Queue depth: 32 Standby timer values: spec'd by Standard, no device specific minimum R/W multiple sector transfer: Max = 16 Current = ? Advanced power management level: 254 DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6 Cycle time: min=120ns recommended=120ns PIO: pio0 pio1 pio2 pio3 pio4 Cycle time: no flow control=120ns IORDY flow control=120ns ... I guess the value would be 254. I will try to set it permanently if I can. Best Regards, S. Sahin