Author Topic: Pi3 can boot from USB... no more SD cards  (Read 1696 times)

Offline ThreeSizes

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Re: Pi3 can boot from USB... no more SD cards
« Reply #15 on: June 09, 2017, 02:31:12 PM »
I have not tried this myself, but here's a couple of thoughts I had about this:

The USB ports and the Ethernet port share the same bus (the Ethernet port is actually a USB device).

The Pi3 has USB2 which is half-duplex so it cannot read and write at the same time and only one device can talk at a time. Performance of the USB flash stick will be affected by network activity and other USB devices and vice versa.

The SD Card is on its own bus and not affected by USB/Ethernet activity.

You are moving all the operating systems read/writes from the SD bus to the already congested USB bus. This also does not take into performance of whatever flash chips are on the USB flash drive. I would expect you to increase the I/O waits on the USB flash drive and increase the possibility of corruption since anything in a I/O wait state is not written to the drive to yet although the process has moved on to other things. Once whatever I/O buffers the Pi has available due to the limited memory would also cause processes to pause while it waits for an I/O buffer to open up. If there is a power-loss with something in an I/O buffer its gone and you'll run the risk of corruption.

In my opinion I would just option for best practices of gracefully shutting down, power protection, and a high-quality SD card.

"And what happened then? Well, in Whoville they say that the Grinch's small heart grew three sizes that day."


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