I tried to turn off TRIM ("discard") on my
ext4 filesystem, but I did not succeed.
I tried to add
nodiscard option into
/etc/fstab, but I can still see this:
# tune2fs -l /dev/md2 | grep discard Default mount options: journal_data_writeback user_xattr acl discard
OS is GNU/Debian, and the disk is an SSD.