My External microSD Card Slot is Faster than the Raspberry Pi 4's. Help Moving microSD Card?

ARM
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I’ve observed what looks to be some disk-access-related bottlenecking. In particular, running a speedtest from either Chrome or Firefox within XFCE attempts to murder the CPU. I see it pegging to 95+ percent, and the speed test results are inconsistent and unusable–they’re far too low, likely because the CPU chokes and can’t keep transcieving data fast enough to give an accurate reading.

tl;dr: I want to take my current boot disk (a microSD) and plug it into the USB 3.0 card reader, so I can get its full speed. Do I have to do anything in software to make that happen, or will the Pi manage to find it even though it’s in a different slot?

More info about why I’m doing this and what equipment I’m using:
Card Reader: > Amazon.com

Kingston Digital USB 3.0 Super Speed Multi-Card Reader for SD/SDHC/SDXC/microSD/MS/Compact Flash CF Cards (FCR-HS4), White, Brushed Nickel

Current Boot Drive:

Amazon.com
Samsung 256GB 100MB/s (U3) MicroSDXC EVO Select Memory Card
Constrained to ~40MB/s in RPi4b microSD

USB 3.0 Attached Card Reader

Test Drive: https://www.amazon.com/Samsung-Class-Adapter-MB-MC64DA-AM/dp/B01273JZMG/ref=sr_1_3?dchild=1&keywords=64GB+Samsung+EVO+Plus+Micro+SD+Card+(Class+10)&qid=1608945291&s=electronics&sr=1-3
Samsung 64GB Evo Plus Class 10 Micro SDXC 80MB/S (MB-MC64DA/AM)
Observed speed attached to RPi4b: ~70MB/s < 80MB/s

speedtest-cli uses about 25-50 percent of the CPU when it’s running the test. With XFCE and Chromium or Firefox open, there’s just nothing left when I try to run the test at speediest.net or fast.com, and I actually start seeing swap space used, and the test reports about half the speed the command line version does. I’ve never seen swap space used without XFCE running.

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Got it. See: Raspberry Pi 4 MSD boot is here - General Discussion - Manjaro Linux Forum

The only two things I had to do were:

  1. Update to the latest firmware; and
  2. Change the device ID in the /boot/cmdline.txt file to my microSD card reader.

There is a horrifying moment when it gave me the “can’t boot” screen, but then it reset itself, found the USB drive, and booted as normal.

Most importantly, pihole came back up, so I can sleep in without anyone running in screaming about the internet being broken.

hdparm is now reporting 73MB/sec - 77 MB/s DIRECT disk reads.

Not sure how that will translate into write improvements, but every little bit helps, I suppose.

At the moment, I don’t have keyboard or mouse in XFCE and can’t login, but that could very easily be a me problem at nearly 1AM. I have a strange setup involving a single keyboard and mouse shared with a switch between two computers.

In the morning, I can try a bluetooth keyboard.
EDIT: Discard. Unplugged cable.

@Darksky , I recall there being keyboard/mouse issues a few months ago? Are those still a thing? I’m on kernel 5.4.81-1.

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If you have issues using wireless keyboard and or mouse and external usb 3 drive then you need to use an longer usb extension cable yo the drive.

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Solved. I had unplugged the hub/switch device the keyboard and mouse are plugged into. :stuck_out_tongue:

There are certain disadvantages to screwing around with your technology after midnight, in the dark.

#RealMenOfGenius

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