Author Topic: External hard drive: powered or unpowered .. does it matter?  (Read 759 times)

Offline Rupert

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External hard drive: powered or unpowered .. does it matter?
« on: January 05, 2015, 04:44:16 PM »
My old external hard drive, which I've always used for backing up all my picture files, is nearly full. I need to buy a new unit very soon, probably something with 3-4 TB capacity.

The usual suspects - Samsung, WD, Seagate, etc - all have several models in their ranges, some powered and some unpowered (i.e. no mains lead, just plug straight into a USB 3.0 port).

Is there any particular reason why one might choose to buy a mains powered external hard drive over an unpowered one, or does it really not make any difference these days?

Offline Nick Peers

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Re: External hard drive: powered or unpowered .. does it matter?
« Reply #1 on: January 05, 2015, 04:59:23 PM »
The big desktop drives tend to be powered separately, while the smaller ones can be powered through USB. Willabong may have a specific idea of why that is - it's possible I guess that performance may be slightly improved if the drive is able to draw power directly from the mains, but I'm not sure by how much. It would still ultimately come down to the drive interface (USB 3.0, plus the internal drive mechanism, specifically its RPM - typically 5,400 rather than 7,200).

One thing to be wary of - I found this out the hard way - is that the way 3TB+ drives are formatted can cause problems if the drive enclosure fails. I had a Samsung drive whose mechanism failed and I had the devil of a time getting the data off the internal drive (which was physically fine), because it had been formatted in such a way you couldn't physically see or access it in Windows when attached via another enclosure.

In the end I was saved by a free data-recovery tool called DMDE (http://dmde.com/), which was the only tool I could find that could recognise the disk structure and format. I ended up paying a small fee for the version that made recovery much quicker and simpler than the free version.

Just something to consider! Ordinarily of course it's the drive itself that fails, not the enclosure, but not in this case! I was extremely lucky I had another large drive to transfer all the data to before formatting the original drive and mounting it internally!
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Offline Willabong

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Re: External hard drive: powered or unpowered .. does it matter?
« Reply #2 on: January 06, 2015, 09:12:40 AM »
You are spot on Nick, also powered drives tend to be more stable than usb driven drives.
I had a usb 2.0 powered drive for a few years, and it would occasionally loose it's connection with my PC for no apparent reason,unplugging and re-plugging the drive allowed the PC to pick it up again. Other than that glitch it ran pretty well. I didn't see any real difference in speed with my other 2 externally powered drives. 
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Offline Rupert

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Re: External hard drive: powered or unpowered .. does it matter?
« Reply #3 on: January 06, 2015, 11:52:04 AM »
Thank you Nick and Willabong for your replies.

Personally I think I'll be happier with another powered drive .. now I want to find one that's switched, or can all powered drives be turned off when not in use?

Offline Willabong

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Re: External hard drive: powered or unpowered .. does it matter?
« Reply #4 on: January 06, 2015, 02:56:04 PM »
No! Not all, so check before buying!
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