Exfat microSD, file disappear when umount

[56yachtcapt67]

Ubuntu Version: 24.04.3

I have a music database that is around 200 GB, I have the music database mapped over to my jellyfin server. Trying to copy this database over to a microSD card for use in my phone. After formatting the micro SD card I mount the card using a thumb driver, then use cp to copy the music over. After cp is done I am able to see all the music, if I umount and them mount it back on the music files disappear.

Any help greatly appreciated.

[celticwarrior]

Are you sure it’s exFAT? (Most Android devices I know don’t support exFAT; iPhone apparently does)

What commands have you run exactly?

[nio-wiklund]

• Did you copy the whole database or ‘only’ part of it?
• Did you let the write operations onto the memory cells finish? At first cp will copy to RAM, and then, slowly, it will be copied to the memory cells, ‘flushed from the buffer’. This can be made faster explicitly with the sync command, and should also be done with the umount command. (When the shell returns to prompt after sync or umount, the buffers should be completely flushed, and the copy process to the memory cells should be complete.)
• When mounting again, are you sure that you mounted the correct partition?
• Maybe there is some confusion. Please read the tips at this link.