I'm running into an issue where if I attempt to flash a microSD card with
sudo dd bs=4M if=some_pi_image.img of=/dev/sdb
It claims to have written the image at about 1.9 GB/s, with output:
1088+0 records in
1088+0 records out
4563402752 bytes (4.6 GB) copied, 2.59837 s, 1.8 GB/s
But has definitely not written to the card.
Stranger still, when I run "sync" after the dd command it returns pretty much immediately. However it's verifiable that when I put the SD card in my pi and boot it up, it's running the old image, and essentially has flashed nothing to the card. I'm careful to umount all /dev/sdbX partitions before running the dd command.
Just for grins I took the microSD card out of the adapter and ran DD again, and got the exact same result, though I know "sdb" is the correct designation, as i can unplug the usb adapter and /dev/sdb will stop showing up when I run "ls /dev/".
I've tried this across 2 cards (one that came with the pi, raspberry symbol and all) and 3 adapters. Running Ubuntu.
Why would "sync" be returning immediately, and nothing be written to the actual SD card?