SAMSUNG 32GB FIT USB 3.0 - Bootable?

[pror21]

SAMSUNG 32GB FIT USB 3.0
Did anyone managed to boot from this stick successfully?
I'm trying to find a 16GB/32GB USB 3.0 stick to boot the OS from it (hopefully for much faster I/O speed ).

[fruitoftheloom]

SAMSUNG 16GB FIT USB 3.0
Did anyone managed to boot from this stick?
I'm trying to find a 16GB/32GB USB 3.0 stick to boot the OS from it (hopefully for much faster I/O speed ).

Only the Raspberry Pi 3B can boot from USB Mass Storage Device and like all Raspberry Pi's only has a USB 2.0 BUS so are limited to that I/O speed.

In the Raspberry Pi Blog a few devices were noted as verified working: https://www.raspberrypi.org/blog/pi-3-b ... orage-boot

[peterlite]

You can boot from the microSD card then, as part of the boot, switch to a USB device. You only need a tiny microSD card for the first part of the boot. A config file redirects the boot. There are descriptions under "using an SSD".

USB is limited to 35 MB/s for disk access. Cheap cards have read speeds about 20 MB/s. Middle priced cards reach 40 MB/s, fore than you need for reads.

Fast cards and fast USB sticks make a difference for random writes, the slowest activity on flash memory. Expensive cards and medium priced sticks often drop back to 10 MB/s or less. A fast USB device might make a huge difference to something like a database update.

I purchased the absolute fastest microSD card for a test Web server. The card has random write speeds slightly faster than USB 2. The super fast microSD card was chosen purely for fast database updates.

[pror21]

But the OS is working most of the time with random read/writes too. That is why i wan't to use a USB stick.
If i understood correctly, you said Raspberry PI 3 USB 3.0 is limited to 35MB/s. Why is that? Is it because of the slow controller / bus?

[fruitoftheloom]

But the OS is working most of the time with random read/writes too. That is why i wan't to use a USB stick.
If i understood correctly, you said Raspberry PI 3 USB 3.0 is limited to 35MB/s. Why is that? Is it because of the slow controller / bus?

Am Raspberry Pi,s as I stated are USB 2.0:

http://www.mikronauts.com/raspberry-pi/ ... ment-howto

This also applies to the 3B

[pror21]

But the OS is working most of the time with random read/writes too. That is why i wan't to use a USB stick.
If i understood correctly, you said Raspberry PI 3 USB 3.0 is limited to 35MB/s. Why is that? Is it because of the slow controller / bus?

Am Raspberry Pi,s as I stated are USB 2.0:

http://www.mikronauts.com/raspberry-pi/ ... ment-howto

This also applies to the 3B

Oh.. okay. Although it seems quite good speed especially for random read/writes, USB 2.0 specification is 480Mbits/s (60MB/s). I guess that is just a theoretical max speed.

Btw it would be very helpful if someone could give me a random read/write benchmark on a USB stick that is done of course from a Raspberry Pi 3B.

[fruitoftheloom]

But the OS is working most of the time with random read/writes too. That is why i wan't to use a USB stick.
If i understood correctly, you said Raspberry PI 3 USB 3.0 is limited to 35MB/s. Why is that? Is it because of the slow controller / bus?

Am Raspberry Pi,s as I stated are USB 2.0:

http://www.mikronauts.com/raspberry-pi/ ... ment-howto

This also applies to the 3B

Oh.. okay. Although it seems quite good speed especially for random read/writes, USB 2.0 specification is 480Mbits/s (60MB/s). I guess that is just a theoretical max speed.

Btw it would be very helpful if someone could give me a random read/write benchmark on a USB stick that is done of course from a Raspberry Pi 3B.

The USB BUS is exactly the same on the 3B as it was on a 2B, why do you think it should be different ??

[pror21]

Nothing, i just forgot to type that . So even from a 2B a benchmark would be very helpful.

[peterlite]

I put a very fast device in a Pi 3 and had read/write speeds hovering around 36 MB/s with occasional 37 MB/s. On USB 3, the device speed is triple that. The 36 MB/s is the Pi 3 maximum speed.

10% of USB 2 bandwidth is reserved for keyboard, mouse, etc. With overheads, a byte uses about 10 bits. 480 megabits becomes 48 megabytes. Take out 5 MB/s for the keyboard reserve, you get 43. Take out another 10% for the file copy overhead, you get 38 MB/s. When copying large files, the speed approaches 38 MB/s.

[peterlite]

https://petermoulding.com/raspberry-pi/ ... rtup-speed
Benchmark copying from very fast SSD, 200 MB/s, to very fast microSD card with 80 MB/s write speed. Produced less than USB 2 transfer speed.