External HD won't boot when connected

[will0407]

My Western Digital 500gb pro used to start up as soon as I plugged it in into my imac (FW800). Now when I plug it in, nothing happens. The only way I can get it to start is by pressiong the power button, but then it boots up and doesn't show on my desktop.
Can someone help me with this please??

 

[richard.mac]

leave it plugged in and startup holding the option key

 

[will0407]

Ok, do you mean plug it in and restart the comp? Or just plug it in, hold option, and then press the power button on the HD?

 

[richard.mac]

OHHH! sorry i misread your post i thought you meant you cant boot into the external drive... as in youve got Mac OS X installed on it.

try turning it off and unplugging it from the mains (if its not BUS powered) and then plug in the firewire cable and turn it on. if it doesnt show up make sure its listed in Disk Utility or you have external disks hidden from the desktop set in Finder's preferences.

if it still doesnt show up you could try using a disk repair app like Disk Warrior. if this doesnt fix it, it may be faulty.

also do you eject the external drive after unplugging it? if you dont the HDD may be faulty and this is why its not showing up.

 

[will0407]

I always unplug it before I go to bed, then when i get up, i wake the imac up, plug in the firewire cable to the back of the external and it usually boots up by itself. I'm currently using it with the FW400 connection, but its noticeably slower.

 

[JNB]

Why are you unplugging the external at all?

 

[will0407]

because when I leave it plugged in overnight, it always "wakes up" and wakes the computer from sleep, and then bright light from the screen always wakes me up.

 

[JNB]

What process are you running that wakes the external up? Remember, it won't do that on it's own, so something you're running on the Mac is looking at the drive for something. Scheduled backups?

 

[will0407]

i've checked for things like that, but it seemed to stop waking up when my HD was unplugged, and I could always just plug it back in in the morning so was never an issue.

 

[richard.mac]

just sleep your Mac and it will spin down and not spin up until you wake your mac. if you want to leave your Mac running overnight eject it using Disk Utility and then mount it when you need to use it again. because you have an iMac just leave it plugged in all the time.

 

[will0407]

it doesn't show up in disk utility though. It seems to power up when It's connected via the FW400, but it's noticeably slower than the FW800