System won't mount /home and /var/cache ext4 partitions in fstab

I use a Chromebook that I have installed EOS on. eMMC memory is not huge, only 16GB, so I need to mount /home and /var/cache on an external 2.5" SSD drive that is connected to a SATA to USB3 interface.
It is possible to mount the filesystems using

mount /dev/sda1 /home
mount /dev/sda2 /var/cache

but when booting system complains about failing to mount /home and /var/cache
for now, every time I boot the system, I need to enter root console and manually mount the partitions in order for the system to boot properly.
What am I doing wrong here?

lsblk -f

[e@candy src]$ lsblk -f
├─sda1 ext4 1.0 806bd83e-fd8c-4478-a819-c7ea74b1b9a8 118G 0% /home
└─sda2 ext4 1.0 90f4bf44-982c-4c89-8456-b7cab2c8dd90 101,7G 1% /var/cache
├─mmcblk1p1 vfat FAT32 NO_LABEL B02C-EA15 510,4M 0% /boot/efi
└─mmcblk1p2 btrfs 931c10bf-be4e-4ff1-80f6-5870f16d26cd 10,2G 26% /var/log


UUID=B02C-EA15 /boot/efi vfat umask=0077 0 2
UUID=931c10bf-be4e-4ff1-80f6-5870f16d26cd / btrfs subvol=/@,compress=zstd,defaults,noatime,space_cac>
#UUID=931c10bf-be4e-4ff1-80f6-5870f16d26cd /home btrfs subvol=/@home,compress=zstd,defaults,noatime,space>
#UUID=931c10bf-be4e-4ff1-80f6-5870f16d26cd /var/cache btrfs subvol=/@cache,defaults,noatime,space_cache,autode>
UUID=931c10bf-be4e-4ff1-80f6-5870f16d26cd /var/log btrfs subvol=/@log,compress=zstd,defaults,noatime,space_>

UUID=806bd83e-fd8c-4478-a819-c7ea74b1b9a8 /home etx4 defaults 0 2
UUID=90f4bf44-982c-4c89-8456-b7cab2c8dd90 /var/cache etx4 defaults 0 2

i am not that knowledged about everything BTRFS subvols can do but on first view it looks like you have the mountpoints doubled…

#UUID=931c10bf-be4e-4ff1-80f6-5870f16d26cd /var/cache btrfs subvol=/@cache,defaults,noatime,space_cache,autode>

UUID=90f4bf44-982c-4c89-8456-b7cab2c8dd90 /var/cache etx4 defaults 0 2

Logically that can not work properly.

  • You will need to remove the btrfs subvols for /home and cache.
  • May bind would work also?
  • But what for using BTRFS? if you do not have any usage for its benefits (in your case the default scheme is not useful).

Deleted the subvolumes @home and @cache. No improvement upon boot.


I use btrfs because it has support for transparent file compression. Useful for saving space in eMMC memory module.

UUID=806bd83e-fd8c-4478-a819-c7ea74b1b9a8 /mnt/ext1    ext4   defaults   0   2
UUID=90f4bf44-982c-4c89-8456-b7cab2c8dd90 /mnt/ext2    ext4   defaults   0   2
/mnt/ext1  /home  none  bind  0  0
/mnt/ext2  /var/cache  none  bind  0  0

must be created before…
But no guaranty i have not tested this :wink:

I’m sorry to say that it did not go as planned. I did as you said and the system was not bootable anymore. Had to reinstall the system. This time I made sure all of it was on the larger external USB SATA drive, no eMMC what so ever involved. I thank you for you attention.