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

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: >

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:
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:
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 or, 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.

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.

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.

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.


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