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I'm very puzzled that when you click "Info" for a SSD drive connected with USB in Disk Utility, it says:

Solid State: NO

Any way to know if a USB attached drive to a Mac is HDD or SSD? Best if you can know in macOS, without third party tool.

It's a 2.5" SSD connected to a USB port.

Any help much welcome.

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    What would you do differently once you know what storage tech is present?
    – bmike
    Jul 14, 2020 at 21:33
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    "It's a 2.5" SSD". How do you know?
    – benwiggy
    Jul 14, 2020 at 21:46
  • why do you answer with useless questions? obviously I know in this case. For example: if I'm remoting into a customer's Mac I sometimes need to know Jul 14, 2020 at 22:49
  • Its pretty easy to identify a 2.5” vs a 3.5” @benwiggy. First is the size and the second is that 3.5” drives require an external power supply because 3.5” drives need 12V DC to spin. As for support - the short answer is “it depends.”
    – Allan
    Jul 14, 2020 at 23:44
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    USB thumb drives also show as "Solid State: No" Jul 15, 2020 at 3:27

3 Answers 3

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It depends. If the external USB controller supports the whole set of ATA commands you can find out if the drive attached is solid state or not. See the following post for several ways to determine if your drive attached is solid state or not.

How to determine if a drive is Solid State via Terminal

Though the driver in macOS is very limited, macOS has this ability to identify the drive attached. The second part that’s required for this to work is the USB to SATA bridge (the chip in the enclosure) must provide this capability. Many off brand vendors use chips that only provide read/write functionality because they are substantially cheaper than quality chips that support more functions.

You can see this in smartmontools (excellent utility for monitoring drive SMART status via the command line) USB support wiki where they state to support USB they need:

  • The USB bridge provides an ATA or NVMe pass-through command.
  • The operating system provides a SCSI pass-through I/O-control which works through its USB-layer.

macOS doesn’t support the pass through of the whole ATA command set (Why it’s limited) and thus you need a special driver for smartmontools. But if the USB device doesn’t suport it, theres no 3rd party driver that will give you this ability.

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MacOS is limited in the data about the drive that it can obtain via USB. If you look, the next line down says "SMART Status: Unsupported".

If you have a drive connected via Thunderbolt, it will support SMART status and accurately report the drive's type.

I suspect that Disk Utility reports that it's not an SSD unless it specifically knows that it is an SSD. And it can't get that information over USB.

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  • Whether or not a drive is SSD is not a value held by SMART. So querying SMART data won’t give you this info.
    – Allan
    Jul 14, 2020 at 23:26
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Go to About this Mac under the apple menu. After clicking on About this Mac you get a small pane with 2 options - choose system report. Rhis bring up a large panel. From the column on the left select "Storage", its about half-way down that 1st column. When you click on that the right side of the panel will list all storage devices connected to your machine, Click on the device you're interested in and facts abiut the device should list. On my machine (2010 iMac) it list the medium type. I think it only lists this for SSD's.

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    I check that, it doesn't say if it's SSD or HDD. Jul 14, 2020 at 23:06
  • interesting. it tells me if I have an SSD. sorry it didn't work for you. I'll keep looking maybe I'll think of something.
    – Natsfan
    Jul 14, 2020 at 23:09
  • Thanks a lot anyway, I've been looking at this for quite some time and it seems there's no way in macOS to tell for sure. There's a way to know by googling for the storage make and model as it shows in system information. Jul 14, 2020 at 23:27
  • you could check the drive speed and compare it to a drive you know is an HDD.
    – Natsfan
    Jul 14, 2020 at 23:34

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