USB powered external hard drives

Discussion in 'MacBook Pro' started by Jatku, Nov 5, 2008.

  1. Jatku macrumors member

    Oct 2, 2008
    So I remember searching for a portable hard drive for my PB and finding out that most Macs need 2 ports to use them, because they have a 500 mA current while many portable hard drives require ~ 600-650 mA. I recently switched out the stock HDD in my late 08 MBP and noticed that my HDD in an external case was fully operational using one USB port, which is still 500 mA. So I have a few questions about this, since I'm looking for backup storage.

    1. Will any model of internal HDD I stick in the external case work with just one USB, or are there different power requirements for them? - Both stock (270 gb, 7200 rpm) and replacement (Seagate 350 gb, 7200 rpm) worked in the case.

    2. Are the portable external HDDs just internal versions with cases? - I thought they were, but it doesn't make sense to me now that I see that mine is powered fine.

    3. Is there any reason to go with a powered external HDD? - I don't move the MBP that often, but less wires and space is nice.

    4. Are there any brands you would recommend? - Including firewire
  2. illegallydead macrumors 6502a


    Oct 22, 2007
    You may have had problems powering them with you Powerbook, but your MACbook spits out plenty of power. Are you saying that the HDD you removed and cased worked fine on the PB or the MBP?

    1) I would think that it depends on the drive, they all will likely have slightly different power demands (5400 would require less than 7200, most likely, but then, a newer 7200 could draw LESS than an old 5400. It is all very drive-specific)

    2) Can't say for sure on that one, but I would assume that the guts of the HDD are the same, it may have a different set of circuitry built in for USB and such, but I would think that it would be easier and cheaper from a business standpoint to just mass-manufacture SATA or IDE drives and put a SATA (or IDE)-to-USB or -to-firewire host in there.

    3) The best reason to go with a powered HDD is cost. Portable (i.e. bus-powered) drives are smaller and use 2.5" drives, instead of 3.5" which is MUCH cheaper per GB. Having a bus-powered drive though, it is bloody nice to be able to move it to another comp to grab files w/o needing the power wire.

    4) I would recommend LaCie. I have a 250GB Little Disk (Sam Hecht model) that has dual FW400 ports, and a retractable USB cable. It is bus-powered and is wonderful! For powered drives, I have a WD My Book Essential (500GB) that has been doing wonderfully, not to mention it is/was cheap. Do some looking around, but these two are wonderful!
  3. Jatku thread starter macrumors member

    Oct 2, 2008
  4. Michael CM1 macrumors 603

    Feb 4, 2008
    I think you may have gotten some bad info, although it may depend on models.

    I bought a Western Digital My Passport 250GB hard drive a few months ago. It's basically a notebook-sized hard drive in a pretty case with a USB port. I have never heard anything about requiring multiple USB ports to power it, especially since I just plugged mine up and formatted it. Maybe this is the case on some much-older computers, perhaps with just USB 1.1.

    I can tell you that plugging it into a USB hub won't work. I tried that with the USB-powered fan that I have with 4 USB ports in it. I got some undervolt error, so I just plugged it up to the actual computer. Luckily, everything else I use will daisy chain with that hub.

    As far as the preference between the bigger, plug-powered hard drives, it's mostly about cost and performance. Those drives are almost all 7200 rpm (as opposed to the smaller ones at 5400 rpm) and cost less per megabyte. The obvious benefits of the smaller drives are fewer cables and more portability.

    I have a dual setup. I have three of the My Book hard drives (the larger, wall-powered ones) plugged in to my AirPort Extreme Base Station. 2 TB of storage over the network. The transfer rate is obviously slower (I connect with 802.11n on a mixed network), but it's NO CABLES at my laptop. I also have a My Passport drive hooked up directly to the computer for other stuff that I might want locally and faster.

    Hope that gives you a little more info.

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