Identifying UASP compliant adapters

Having fumbled my first attempt to get a "good" usb-sata adapter for eventual use with a Pi4 it's time to ask again for advice.

Very few usb3-sata adapters disclose enough information to ascertain their level of UASP support, but there seem to be a few that might have hope. Here are a few possibilities:

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Other candidates would be welcome.

Does the USB3.1 Gen1 or Gen2 notation have any significance?

Thanks for reading!

bob prohaska

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bob prohaska
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bob prohaska kirjoitti 21.6.2020 klo 4.38:

USB 3.1 Gen1 is 5Gb/s , USB 3.1 Gen2 is 10Gb/s

But as you're using a SATA HDD/SSD in it, that speed is topped off at

6Gb/s (SATA III speed) anyway.
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tumppiw

lsusb -t says driver=uas.

Caveat. I'm not a 100% sure about matching USB device with HDD, I'm assuming this is the correct one.

I don't really understand what "UASP" is or why you care. The above device works with the Pi4 and a 2.5 hdd. I have another one, also worked with Pi4 and ssd in past but not plugged in currently.

Reply to
Pancho

Speed.

Reply to
Andy Burns

OK, my speed concerns were limited by 1 Gb/s network. My adapters were good enough to do that.

Reply to
Pancho

A little more than speed in terms of bits per second......

It permits commands to be issued before the preceeding command completes. In the meantime the bus is free for other traffic.

It can make a difference with small random reads and writes. That situation arises in swapping, especially with multiple disks.

Thanks for replying!

bob prohaska

Reply to
bob prohaska

That's what I'm looking for. Alas, it's not found on amazon.com

Thanks for writing!

bob prohaska

Reply to
bob prohaska

Is the instruction set the same?

Understood.

Thanks for writing,

bob prohaska

Reply to
bob prohaska

I can confirm from having used them that these devices support UAS:

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(2.5" HD/SSD enclosure...and it's clear!)

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(dongle for reading drives...includes a wall wart to power 3.5" & 5.25" devices)

_/_ / v \ Scott Alfter (remove the obvious to send mail) (IIGS(

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Reply to
Scott Alfter

It's USB Attached SCSI (vs. Serial Attached SCSI (SAS) that's common in servers nowadays or the really old-school parallel SCSI well-known to Apple users and such). It's faster than the bulk-only transport mode provided by the USB mass-storage class, probably because there's less translation of commands and responses between the host and the storage device.

How much of a difference that would make on a Raspberry Pi (especially the pre-RPi4 models) is unclear, but it's a win for most desktop PCs running an up-to-date OS. (Linux supports UAS. Windows 10 supports UAS, but Windows 7 doesn't.)

_/_ / v \ Scott Alfter (remove the obvious to send mail) (IIGS(

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Reply to
Scott Alfter

That is most helpful.

Will either device support scatter-gather on a Pi4?

Thanks very much for writing!

bob prohaska

Reply to
bob prohaska

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.

_/_ / v \ Scott Alfter (remove the obvious to send mail) (IIGS(

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Reply to
Scott Alfter

See

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---druck

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druck

Near as I can see that article describes how to turn off UAS if it's suspected of being incompatible with the drive. If performance gets better, the drive _is_ incompatible with UAS.

Couldn't recognize any sign of a definitively affirmative test...... What am I missing?

Thanks for posting!

bob prohaska

Reply to
bob prohaska

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.

_/_ / v \ Scott Alfter (remove the obvious to send mail) (IIGS(

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Reply to
Scott Alfter

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 +
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+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

Reply to
bob prohaska

TRIM is a command sent to the drive, defined in the USB standard. How could Linux handle it any differently? Frankly, I think it's telling that Startech mentions "Kernel 2.6.3", which was released in 2004. They might be just a little bit out of touch. Like two decades or so.

Reply to
Anssi Saari

That's discouraging....I'm not up on Linux kernel numbers, so it didn't register with me.

I've ordered a Startech usb3-sata3 adapter, since I'm using a mechanical HDD the lack of TRIM support won't be an immediate issue. I'd still like to find a correct implementation of UASP for use on a Pi4.

Thanks for writing!

bob prohaska

Reply to
bob prohaska

Actually, I don't want to be too hard on Startech. They did give a knowledgeable answer about the UASP support in their devices and that's actually great and really enough to know if their stuff works in Linux or not. Personally I think it'd be great if companies went with that wrt Linux, i.e. just say something like "we support standards x, y and z so if Linux supports those it'll work fine." At least when it's a question about standardized protocols.

Reply to
Anssi Saari

or are they stating the kernel version it is supported 'FROM' thereby showing that they actually been around some time?

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Alister

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