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I want to use an ssd to use raspberry pi with home assistant and I’ve found some information that an external ssd may require too much power and be unstable with the RP4. Is this true? Is one type of ssd better than another?

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  • ALL USB port total can only have 1.5a or 1500ma, and that is assuming the main power supply has that much extra power. You will have to know how much power your SATA or NVME drive uses plus the adapter.
    – cybernard
    Sep 26, 2023 at 18:13

2 Answers 2

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I've found the WD Green SSD drives work reliably with the Pi4 some other makes can hang occasionally unless a powered hub is used. I have 10 Pi's using this configuration successfully, all booting from the SSD.

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  • Appreciate the advice Sep 8, 2023 at 16:53
  • Make sure to use a USB3 to SATA adaptor that works with the Pi not all are suitable
    – Bra1n
    Sep 10, 2023 at 7:00
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If you are using a SATA drive you need some kind of enclosure with USB adapter, since the Pi does not have a SATA port. This is a bit silly unless there is some reason you need to use some specific make/model that is SATA based; it can't be any faster than a USB drive since it is still using the USB port. The same goes for NVME drives.

Lots of small portable USB SSDs will work with the Pi without external power. Before you buy, try and find out what the power consumption is. You also have the option of using a powered USB hub, then it won't matter and any USB drive should work. This may be a bit awkward, but it is less goofy than the SATA enclosure (which would also require external power).

Generally if you search, eg., "samsung t7 power consumption" you will find a review somewhere giving some power consumption numbers. Sometimes these are just the manufacturer's spec, sometimes they are from actual independent tests. The figure is often in watts, which to convert to mA is:

Watts * 1000 / Voltage

The aforementioned T7 is spec'd to not consume more than 7.5 W, which @5V is 1500 mA. Considering that the most you can supply the Pi4 with is 3000 mA and that it seems to test at ~6.5 W (@5V, 1300 mA) peak, there is a good chance that this will work, but since this might be a bit idealized, not a guarantee. That said, you probably won't find a drive that takes much less (as generally they are going to be designed to use the USB 3.0/1/2 max).

If worst comes to worst and you need a powered USB hub, these are inexpensive and very commonplace.

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  • Thanks. Can you expand into be powered usb hub? Is there an example of one? Sep 8, 2023 at 16:53
  • Sorry, also, I’m looking at the Samsung t7 here walmart.com/ip/… Sep 8, 2023 at 17:06
  • I've added a couple of paragraphs at the end. WRT to powered hubs, these have been around for years and are very easy to find, they sell them in drugstores here along side headphones etc. and there should be an endless list available to you online.
    – goldilocks
    Sep 9, 2023 at 14:47

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