If you open up the housing of most 2.5 inch external HDDs, (superfluous: those that don't need and extra power source) the disk inside can be used as an internal HDD, provided it has a SATA connection. One removes the SATA-to-micro-usb-3.0-connector, et voila! It seems that some HDD's (by Toshiba and Verbatim for example) have a micro USB 3.0 card, so those can NOT be used inside laptops or network devices.

Question: How can we know before opening or better yet, before buying whether such an external portable HDD has a SATA connection and nót a micro USB 3.0 card? So, what specific characteristic in the specification does one look at? Interface?

Follow-up: What other issues might prevent us from shucking the HDD's?

  • toshiba-storage.com/products/… 78 x 109 x 14 mm (including its enclosure). They won't tell you the dimensions of the drive inside the enclosure because they don't expect you to shuck it.
    – Gantendo
    Nov 22, 2021 at 11:55
  • superuser.com/questions/1241862/…
    – Gantendo
    Nov 22, 2021 at 12:10
  • 1
    There's another caveat, even if everything fits mechanically & electronically - sometimes External enclosure 'fake' the bock size [this use to be for simplicity/compatibility on older computers]. You can use the drive directly in a computer, but you will need to fully re-format before you can use it so it won't work if there's data on it you need.
    – Tetsujin
    Nov 22, 2021 at 12:18
  • 3
    @Gantendo - they also won't tell you the dimensions of the drive inside because the spec is not guaranteed to be fixed. They'll use whatever drives they have available at the time. It all gets hidden in a 'sekrit box' that few consumers will ever think to look inside ;)
    – Tetsujin
    Nov 22, 2021 at 12:21

1 Answer 1


Not every.

It depends really on the design of the disk. Some may have SATA port, or some may have different electronics between port and the disk inside.

Mostly many of them will be SATA but you are not sure unless opening the disk (and having void warranty) and checking, and connecting it would be a sure situation as this may be modified SATA.

So unless you open the disk, connect it and check the data on disk - you are unsure.

The thickness is the second parameter which can block you from putting the disk into a laptop.

Also laptop can have or will not have desired space for each drive's thickness.

  • Also, note that if you build consumer external hard drives, you probably don't walk into a hardware store and buy 20 HDDs off the shelf – you talk to the people making or distributing the SSDs and make a contract to deliver their drives at scale. Typically, you want to get them cheaper than retail, because they're going to be used in lower-performance settings, anyway. So, if not simply always buying the stock surplus of last-generation drives, you might make an arrangement with the HDD manufacturer to deliver drives that were categorized as lower-performing during manufacturing testing. Nov 22, 2021 at 12:35
  • (hard drives use error-correcting codes extensively, because even the most expensive server hard drive makes a lot of bit errors, physically, which mustn't be left uncorrected; luckily, math allows us to correct bit errors through computational effort and added redundancy, i.e. more bits to store the data than the data had bits). There's variations in the amount of raw bit errors, and thus variations in the maximum sustained read speed including iterative error correction schemes, of hard drives. You don't need a great fast hard drive for a USB3 use case. So, you get the ones that the vendor Nov 22, 2021 at 12:38
  • didn't feel like putting on the market as HDDs on their own – to protect their brand. Wouldn't want to {insert brand name here} series of {insert high-end HDD series name} to perform badly in a test, would you? But that also means that they can drop features from the platter that the USB host doesn't use anyways. Smaller/slower caches, less reporting, no command reordering … would all be legal to have in an external drive. Nov 22, 2021 at 12:40
  • 1
    So, buying an external 2.5" USB drive to take out the sata drive within – not a great idea, to be honest. Nov 22, 2021 at 12:41
  • @MarcusMüller I would guess that OP has that drive laying around gathering dust and wondered if they could use it as an internal drive.
    – Gantendo
    Nov 22, 2021 at 12:47

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