When I run fstrim --all -v a few times in a row it doesn't seem to be working as expected. Every time it reports that it processes the same number of bytes:
root@pc:~# fstrim --all -v
/boot/efi: 503.2 MiB (527675392 bytes) trimmed on /dev/mmcblk0p1
/: 0 B (0 bytes) trimmed on /dev/mmcblk0p2
root@pc:~# fstrim --all -v
/boot/efi: 503.2 MiB (527675392 bytes) trimmed on /dev/mmcblk0p1
/: 0 B (0 bytes) trimmed on /dev/mmcblk0p2
root@pc:~# fstrim --all -v
/boot/efi: 503.2 MiB (527675392 bytes) trimmed on /dev/mmcblk0p1
/: 0 B (0 bytes) trimmed on /dev/mmcblk0p2
Both partitions are sitting on the same built in SSD and mounted in the fstab as follows
/dev/disk/by-uuid/UUID1 / ext4 defaults,noatime 0 0
/dev/disk/by-uuid/UUID2 /boot/efi vfat defaults 0 0
Is this a sign of an issue with the media? Is it something to do with vfat formatting?
I run Ubuntu 20.04 64bit server, 5.4.0-33-generic
EDIT:
$ lsblk -D
NAME DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
mmcblk0 0 4M 74M 0
├─mmcblk0p1 3145728 4M 74M 0
└─mmcblk0p2 3145728 4M 74M 0
mmcblk0boot0 0 4M 74M 0
mmcblk0boot1 0 4M 74M 0
This is a motherboard embedded 64G SSD (not an SD card).
It seems to be unable to trim the whole partition (511M - 8M = 503M), I wonder if the small size makes the difference
df -h | grep dev/m
/dev/mmcblk0p2 49G 7.5G 40G 17% /
/dev/mmcblk0p1 511M 7.8M 504M 2% /boot/efi
