froky

sustainable read speed for SSD possible?

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I have a project where I need to allow a user to connect an SSD (UASP) to a device (which has an embedded Mini ITX PC) and stream data (uncompressed video) at 370 MByte/second read speed.

I need to allow the user to connect the SSD to his own PC and create any (uncompressed video) content he wants and send it from his PC to the SSD, which he will later connect to the custom device for streaming his content.

In other words, files are going to be saved and deleted from the SSD by the user, however the read speed must remain the same and not go below 370 MByte/s for the device to be able to stream the files.

Is this possible? Leaving any damage or wear from old SSD aside.

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Pretty much any decent SSD these days will happily sustain 370MByte/sec read speed, that's not a problem. UASP, I'm not so sure about. I've never gotten over 250MB/sec over USB 3.0 but I don't have UASP.

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Pretty much any decent SSD these days will happily sustain 370MByte/sec read speed, that's not a problem. UASP, I'm not so sure about. I've never gotten over 250MB/sec over USB 3.0 but I don't have UASP.

Have you tried a SSD over a USB3.0 port, or a USB3.0 memory stick? The latter doesn't support the 5 Gbit/s (625 MB/s) of the USB3.0 yet, only hard drives connected via the USB3.0 port can, as far as I know.

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Yes, SSDs and memory sticks were what I tested. I'm not sure what else you can get 250MB/sec from on a USB port if it isn't an SSD or USB memory sticks...

Both memory sticks and SSDs have supported 5Gbit/s over USB 3 since the day it came out. I don't know of anything that doesn't support it, there's no point in implementing USB 3 on any device if you're not going to implement SuperSpeed...

[Edit]

These tests from 2012 show SSDs topping out at just under 370MB/sec over USB 3 UASP, but only being able to reliably sustain about 300MB/sec:

http://www.tomshardware.co.uk/usb-3-uas-turbo,review-32467-4.html

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I've been told that USB memory sticks aren't there yet and can't really do SuperSpeed and reach the speeds of SSDs connected via USB3 ports.

Maybe I have been given false info?

I'd be glad to be proven wrong, means I could decrease the size of the memory device for the user and have him use a familiar piece of hardware for his work.

Edited by froky

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I've been told that USB memory sticks aren't there yet and can't really do SuperSpeed and reach the speeds of SSDs connected via USB3 ports.

Maybe I have been given false info?

I'd be glad to be proven wrong, means I could decrease the size of the memory device for the user and have him use a familiar piece of hardware for his work.

I'm sure I posted a reply here earlier, which seems to have disappeared. Nonetheless: Indeed, you seem to have been given false information. USB memory sticks have been able to make use of SuperSpeed for several years now, with the following flash drive from 2013 producing 190MB/sec:

http://www.storagereview.com/sandisk_extreme_usb_30_flash_drive_review

And others from 2013 going up as far as 300MB/sec:

http://www.tomshardware.co.uk/usb-3.0-thumb-drive-review,review-32737-2.html

It does seem from more recent tests about 450MB/sec is the maximum for USB 3.0, and 700MB/sec achievable for USB 3.1 (Gen 2):

http://techreport.com/review/27906/a-first-look-at-usb-3-1-performance/2

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From what you said they haven't given false information actually. "Superspeed" or not, 190 or 300 MByte/s seems still behind the typical SSD speeds.

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I disagree - anything over 20-30MB/sec is SuperSpeed, and you said:

USB memory sticks aren't there yet and can't really do SuperSpeed and reach the speeds of SSDs connected via USB3 ports.

Back in 20013, 300MByte/s was higher than SSDs connected via SATA 300, let alone USB.

The pages I quoted showed a Patriot Magnum USB 3 thumb drive from 2013 doing 305MB/sec read and 159MB/sec write.

The following USB 3 SSD from 2015 does "Close to 300MBps" read and "almost 160MBps" write:

http://www.cnet.com/uk/products/samsung-portable-ssd-t1/2/

Other SSDs on that page do 220MB/sec reads, and two hard drives in RAID do 210MB/sec reads. How is a 305MB/sec USB stick "behind"?

You also said:

The latter doesn't support the 5 Gbit/s (625 MB/s) of the USB3.0 yet, only hard drives connected via the USB3.0 port can, as far as I know.

300MB/sec is faster than any hard drive you can buy, with most hard drives being 100-200MB/sec. If you consider a 300MB/sec USB stick "not supporting the 5Gbit/s of USB 3" then a 100MB/sec hard drive isn't exactly supporting it any more is it?

If you don't agree with the above then it'd be interesting to know what specifically you actually define as "really do SuperSpeed"

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I disagree - anything over 20-30MB/sec is SuperSpeed,

Let me rephrase then, or repost what I said:

"Superspeed" or not, 190 or 300 MByte/s seems still behind the typical SSD speeds.

Now,

SuperSpeed is for speeds up to 650MB/s. SSDs apparently can get close to to that max speed. they sure seem to go over my 370 requirement. http://www.overclockers.com/inateck-ua1001-usb-3-0-to-sata-adapter-review/

USB sticks don't. I don't know what the case was in 2013. We can call both of them SuperSpeed and to be correct they are and I was wrong to word it that way, but that's not important here, what is important is I need 370 Mbyte read speed, like I've said already, and USB sticks can't get there yet it seems.

I meant SSD, not hard drive, it was a typo.

In summary, some people claim SSDs can do the speeds I need, without an adapter though. Testing my own notebook's SSD I get about 500 MB/s sequential read speed. I've also found out that this likely doesn't change over the lifespan of the SSD ,unlike HDD.

As much as I would love to go with USB sticks which are mor familiar to users, even though they are technically SuperSpeed, I can't find one which could do the 370 MB/s minimum read speed.

I guess the only question left now is, unless someone has a different info on the above, what about when connecting the SSD via a USB adapter?

Edited by froky

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Let me rephrase then, or repost what I said:

"Superspeed" or not, 190 or 300 MByte/s seems still behind the typical SSD speeds.

Those were just examples. By definition, USB sticks are SSDs.

Now,

SuperSpeed is for speeds up to 650MB/s. SSDs apparently can get close to to that max speed. they sure seem to go over my 370 requirement. http://www.overclockers.com/inateck-ua1001-usb-3-0-to-sata-adapter-review/

Superspeed won't ever get close to 650MB/sec, just like USB2 devices never got anywhere near 480Mb/sec.

USB sticks don't. I don't know what the case was in 2013. We can call both of them SuperSpeed and to be correct they are and I was wrong to word it that way, but that's not important here, what is important is I need 370 Mbyte read speed, like I've said already, and USB sticks can't get there yet it seems.

I meant SSD, not hard drive, it was a typo.

USB sticks (ignoring the fact they are SSDs by definition) can be just as fast if not faster - take for example this Visiontek USB stick that calls itself an SSD - 440MB/sec reads and writes.

Ultimately I'm not recommending a USB "flash drive" but the point all along has been there will always be devices faster than others. The interface is the limiting factor, and both "flash drives" and "traditional" SSDs will happily max out the interface - which in turn will be nowhere near the 625MB/sec theoretical interface speed.

In summary, some people claim SSDs can do the speeds I need, without an adapter though. Testing my own notebook's SSD I get about 500 MB/s sequential read speed. I've also found out that this likely doesn't change over the lifespan of the SSD ,unlike HDD.

Actually, read and write speeds with SSDs will vary far more over their lifespan than HDDs. HDDs will show zero change in performance over it's life whereas SSDs do degrade. However this is going off on a tangent, HDDs don't offer the performance you want to begin with so it really doesn't matter if they don't degrade.

As much as I would love to go with USB sticks which are mor familiar to users, even though they are technically SuperSpeed, I can't find one which could do the 370 MB/s minimum read speed.

I guess the only question left now is, unless someone has a different info on the above, what about when connecting the SSD via a USB adapter?

You will be entirely at the mercy of the adapter - some adapters max out at 220MB/sec, while others as you have seen exceed 400MB/sec. Similarly, some USB controllers will show the same limitations. This is why I stated in my first post that I'm not certain you can reliably sustain such speeds over USB regardless of the device used. In practice, almost all USB "SSDs" are SSDs connected via an adapter so I'm unsure what you're asking. There are, increasingly, devices with native USB interfaces or USB bridges on the host board but that is more common with flash drives than SSDs.

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