Scott Alfter  wrote:
> In article , druck   wrote:
>>On 22/06/2020 20:45, Scott Alfter wrote:
>>> In article ,
>>> bob prohaska   wrote:
>>>> That is most helpful.
>>>>
>>>> Will either device support scatter-gather on a Pi4?
>>>
>>> How would you determine this?  Is it something that will show up in a
>>> logfile?  (If it's enabled for a device, UAS pops up in /var/log/messages.)
>>> Does it depend on the storage device in use?  IIRC, I have a Samsung Evo
850
>>> in the enclosure.  I have some WD Blues & Greens I can test with the
dongle.
>>
>>See https://www.raspberrypi.org/forums/viewtopic.php?t=245931
>
> OK...so that's something I can't answer for the devices I listed, as I don't
> have a Raspberry Pi 4 to test against.  Lots of 3s, a few of the original
> Model Bs, and a Zero W, but not a 4.
>

I'm in the same boat for now; I'm shopping for a Pi4 but don't want to
make another mistake on selecting a disk adapter..

A question to the folks at Startech produced a somewhat encouraging reply:

[quote]
....
If you intend on only using a 2.5" drive, you could use something like our
+https://www.startech.com/HDD/Adapters/USB-3-SATA-adapter-cable-with-UASP~USB3S
2
+SAT3CB . It is USB powered so that is why it will only work with 2.5" drives.

That being said, while it does support UASP, it does also depend on the
hardware
+and operating system you are working with. The USB controller on the raspberry
+Pi needs to also support UASP and so does the operating system itself. Some
+versions of Linux running Kernel 2.6.3 and higher can take advantage of UASP
+but it is limited to a very small set of supported hardware so just keep that
+in mind.

With regards to support for Trim, the adapter I recommended does not support
+Trim. However, it won't matter if I recommend one that does or not because
none
+of the products we have that support it, support it in Linux unfortunately.
....
[endquote]

The writer seems to understand the question, and answers it clearly. That's
a better start than many vendors. I'm a little baffled at the last paragraph,
however. Does Linux handle trim differently than, for example, Windows?

Thanks to all for reading,

bob prohaska

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