I have 4 of these drives in a RAID5 array, under Gentoo GNU/Linux, and connected via Firewire 800.
Last week I returned one of them under RMA, after it mysteriously stopped working. While it was away (i.e last night) another one of them decided to make itself unrecognisable. Its LED just kept flashing, but I could not hear or feel the drive units start up. I was facing the loss of 2TB of data...
After cursing and grinding my teeth, I decided to do some research, and one issue that cropped up was the external PSU. Seemingly its green LED will flash if there is a problem, while it is not connected to the drive unit...mine didn't.
Seemingly, once connected to the drive unit, it will flash if there is a problem with the drive unit's power regulator...mine didn't.
However, it did go noticeably dimmer, when the power switch on the back of the unit was switched to the ON position. So, I swapped it for another identical PSU, and it came up straight away, with the PSU LED not missing a beat.
So if your drive starts up and just flashes its front LED, listen and feel for the drive units buzzing. If you don't feel that, check the LED on the external PSU brick - it could be a dead PSU.
