Problems with external hard drives

[David-G]

(a) Is the consensus of opinion that for a single 1TB external hard drive, and with no other USB devices attached, it is alright to rely on power from the USB port? (i.e. without mains power)

(b) Same question, but for 2TB?

Thank you Sydney for your very helpful post.

[MrGongGong]

(a) Is the consensus of opinion that for a single 1TB external hard drive, and with no other USB devices attached, it is alright to rely on power from the USB port? (i.e. without mains power)

(b) Same question, but for 2TB?

Thank you Sydney for your very helpful post.

Yes
i've never had any problems with this on either 1TB or 2TB drives

I guess if you were running a whole pile of other USB devices at the same time you might have problems

[Bryn]

The 'problem' I have had is with a 2TB drive if used with a 1TB drive also in play. On its own the 2TB drive works fine. It still works with the 1TB also in use, but runs slowly and with a lot of clicking. Rather than put unnecessary stress (and possibly even strain) on the 2TB drives mechanics, I now tend to attach just that, copy to the PC's hard drive, then safely remove the 2TB drive, plug in the drive I want to copy to and move the file from the PC's hard drive to that.

[Dave2002]

Perhaps only slightly related, though I don't feel like running exhaustive tests to check, is the behaviour of some Mac systems when USB devices, such as memory cards, are plugged in. In some versions of Mac OS, the devices won't always appear on the desktop, depending on the settings. This means that a user may not know whether it is safe to remove a USB connected device. Further, even if the settings are OK, I've noted recently that on my MBP that if the machine is in an idle or sleep mode, then it doesn't acknowledge cards which are plugged in while in that state.

It seems safe enough to unplug the USB devices if in that state and icons don't appear on the desktop, then once the desktop appears on the screen, plug the USB device back in, whereupon the appropriate icon will appear on the desktop and the device should work satisfactorily.

Probably most of us won't be plugging/unplugging hard drives into laptops too often, though some might. However, I think that similar behaviour might be observed with some Mac desktop systems, and this could affect USB external drives.

[David-G]

The 'problem' I have had is with a 2TB drive if used with a 1TB drive also in play. On its own the 2TB drive works fine. It still works with the 1TB also in use, but runs slowly and with a lot of clicking. Rather than put unnecessary stress (and possibly even strain) on the 2TB drives mechanics, I now tend to attach just that, copy to the PC's hard drive, then safely remove the 2TB drive, plug in the drive I want to copy to and move the file from the PC's hard drive to that.

Thanks Bryn. I cannot do that, because my "Ultrabook" with solid-state drive only has about 60 GB (!), and my "antique" XP laptop does not have much more. So I have to plug both external drives in when copying from one to the other. This indeed led to "clicking" as you said, and appears to have resulted in corruption of data (which was why I started this thread). Taking advice from here I have since been plugging both drives into a USB hub with external power. That seems to have gone alright.

I was then wondering if the powered hub was still required when backing up from the PC's hard drive to the external hard drive in the first place. I am reassured that the answer appears to be no.