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rk25123
Jan 17, 2013, 05:24 AM
Hello, I have a WD external hard drive connected directly to my Mac Pro (10.8.2, all updates) via USB, the drive won't mount on startup, and it won't be listed until I unplug it and replug it. The strange thing is that sometimes it does mount normally. I have 2 others WD external drives (different model) which do not present the issue. Any ideas? Thanks for the help!



JimmakoS
Jan 17, 2013, 05:26 AM
What is the format of your drive?

justperry
Jan 17, 2013, 05:35 AM
Bus Powered?
If so it's a possibility it draws too much power, I think if you open System Profiler you can see the amount of mA it uses under Hardware-USB.

rk25123
Jan 17, 2013, 06:19 AM
What is the format of your drive?
The drive is NTFS (so are the other 2)
Bus Powered?
If so it's a possibility it draws too much power, I think if you open System Profiler you can see the amount of mA it uses under Hardware-USB.
That seems to make sense, since the other two drives have their own power supply and this is powered from USB... But then, why does it sometimes mount normally and others I have to unplug and replug it? In System Profiler it says:
available power: 500 mA
power required: 500 mA
So it should work fine...

justperry
Jan 17, 2013, 10:32 AM
The drive is NTFS (so are the other 2)

That seems to make sense, since the other two drives have their own power supply and this is powered from USB... But then, why does it sometimes mount normally and others I have to unplug and replug it? In System Profiler it says:
available power: 500 mA
power required: 500 mA
So it should work fine...

Some drives need an Y-USB cable, I have one and it does not work on a single USB port, it is a Toshiba HD and it sucks a lot of juice from the USB ports, it won't even start on my powered USB 1 amp hub on one USB connector.

But, long ago I had issues as well with one drive, plug it in, did not work, get it out and in again and it did, this also on one cable.