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Question: cannot format external hard drive OS 10.13.3

Trying to format a WD 1TB external hard drive (formatted with Windows) with MacBook Pro via the erase command and with Apple Mac OS Extended (Journaled) selected in disk utilities did not work. The disk title disappeared. An error message said "not enough memory".

Mac Pro, Mac OS X (10.6.8), 2.6Ghz,2Gbyte

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Mar 12, 2018 9:47 AM in response to Lanny In response to Lanny

Lanny wrote:

The suggestion is that perhaps your WD drive needs to be hooked to an external power supply of its own, that it's not getting enough power from your laptop.

Never seen a WD external bus-powered drive with any means of connecting an external power supply. I did buy one over a decade ago and the instructions said that it might require use of a dual-plug USB cable designed to extract power-only out of a second USB port. I bought another USB external drive that came with a cable like that.

Most of the newer ones can easily be powered by a single USB port. I've got one (Seagate though) that System Report says is asking for 160 mA connected directly to the port or 100 mA if connected to a hub. That can be done if the enclosure is carefully matched to the drive (i.e. designed that way by the manufacturer). External enclosures often ask for "worst case" power provisioning, assuming that the drive will be a power hog.

Mar 12, 2018 9:47 AM

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Mar 12, 2018 10:46 AM in response to Lanny In response to Lanny

Lanny wrote:

Was just trying to clarify kaz-k's remarks to the OP.

But, yes there are WD drives that accept external power:

User uploaded file


Ah - but that's a desktop drive. I've even got a couple of WD external desktop drives, and they require use of a 12V power supply. But bus-powered drives are another matter. Some older ones do have a coax port for a 5V external power supply, but this is becoming exceedingly rare these days since most drives can easily power off of a 500 mA USB port.

If the OP has one of those, it won't even communicate at all unless there's an external power supply, which would have come in the box.

Mar 12, 2018 10:46 AM

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Question: cannot format external hard drive OS 10.13.3