MacBook Pro ejecting External Hard Drive when plugging in other USB cables

[Broph]

I have a 2011 MBP (2GHz), with a Seagate 1TB USB powered external hard-drive which is constantly backing up via. Time Machine.

Just now, I got my iPhone sync cable and plugged it into the USB port on my MBP, and then I got the error message pop up saying that my external hard-drive was incorrectly removed and may be corrupt etc. I noticed my external hard drive was just flashing, meaning that it considered itself as 'ejected', but still detected the power supply.

I found this slightly odd, as I didn't have my phone plugged into the other end of the cable, and yet, just the cable was still enough to stop the power supply to the hard drive.

Anyone else experienced this, or has any suggestions?

 

[shootist]

Mac notebooks are notorious for not being able to supply power to 2 USB powered devices at the same time. So whenever you connect a device that charges its internal battery from the USB port the Mac must disconnect whatever other device is connected and drawing power from the USB ports.

The only way around that is to get an external that is AC powered for your time machine back drive.

You'll actually be glad you do this as the USB powered drives can get disconnected at any time causing your TM backup to fail and corrupt the drive at the same time.

 

[Broph]

Ah OK, thanks for that.

I picked the USB powered one for portability, but may have to look into an AC powered one.

Thanks for the info.

 

[Eonrunner]

I'm having this exact same issue despite having a belkin thunderbolt hub and only connecting/disconnecting a/c powered devices to/from it. The hub is always plugged in and so are the devices (glyph drives, red mag readers)

What is the work around for this issue?? I really need some help here and thank any(every)one in advance.