After running Debian for two years, the USB stick of my ERLite-3 finally broke with many write errors.
ERLite-3 has compatibility problem on the USB port. Very few USB sticks are available on it. I found some articles and they all say “Sandisk Cruzer Fit” works well.
I had bought a 16GB model on Amazon… and… YES! It worked!! I should buy some spares!
FYI: Gentoo people says that sectors before 2048 contain something, but I could simply fdisk, mkfs and cp to recover the system.
Don’t forget to keep the half of disk empty. That’s for “overprovisioning”. You can create empty partition. And never touch the partition.