Dropbox is not letting me move its storage off the (small) eMMC

Question

I'm having problems with a fresh install of LMDE on an acer Travelmate (TMB117 M C587) that has a 32gb eMMC drive and a 1tb hdd. specifically, I can't move dropbox's storage off the eMMC onto the 1tb drive.

the error reads

To sync your Dropbox, move your Dropbox folder to a partition with a >compatible File System. Dropbox is compatible with Ext4.

which leads me to conclude either Dropbox has lost it... or far more likely, I messed up somewhere along the way. Or something else entirely is going on with my laptop that I'm just missing.

parted -l and /etc/fstab both show that both relevant drives are formated to ext4.

parted -l does show two other drives (/dev/mmcblk0boot0 and /dev/mmcblk0rpmb) that are lacking in a proper file system. Given the size, I'm operating on the assumption that they're read-only memory on the motherboard for firmware type things (possibly the TPM module?) and not something I should be trying to 'fix' with a makefs.ext4 or similar.

I'm also trying to figure out why dropbox would care about them at all... or why it would be kicking up that error.

sudo parted -l:

Model: ATA ST1000LM035-1RK1 (scsi)
Blockquote
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name     Flags
 1      1049kB  1000GB  1000GB  ext4         primary


Error: /dev/mmcblk0rpmb: unrecognised disk label
Warning: Error fsyncing/closing /dev/mmcblk0rpmb: Input/output error
Retry/Ignore? i                                                           
Model: Generic SD/MMC Storage Card (sd/mmc)
Disk /dev/mmcblk0rpmb: 4194kB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 

Error: /dev/mmcblk0boot0: unrecognised disk label
Model: Generic SD/MMC Storage Card (sd/mmc)                               
Disk /dev/mmcblk0boot0: 4194kB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 

Error: /dev/mmcblk0boot1: unrecognised disk label
Model: Generic SD/MMC Storage Card (sd/mmc)                               
Disk /dev/mmcblk0boot1: 4194kB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 

Model: MMC M52532 (sd/mmc)
Disk /dev/mmcblk0: 31.3GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system     Name  Flags
 1      1049kB  538MB   537MB   fat32                 boot, esp
 2      538MB   29.2GB  28.7GB  ext4
 3      29.2GB  31.3GB  2056MB  linux-swap(v1)

/etc/fstab

# UNCONFIGURED FSTAB FOR BASE SYSTEM
proc    /proc   proc    defaults        0       0
# /dev/mmcblk0p1
UUID=1473-7E8C  /boot/efi       vfat    defaults        0       0
# /dev/mmcblk0p2
UUID=18e97241-975e-4cb8-8a36-ca7298d2f255       /       ext4   
rw,errors=remount-ro    0       1
# /dev/mmcblk0p3
UUID=9475a0d3-967d-41bb-a33c-67862702548e       swap    swap    sw      >0       0
# /dev/sdb1
UUID=c0ee208c-1a84-4457-a887-0eecd6876e3a       /cake   ext4    rw,errors=remount-ro    0       0

Answer 1

Dropbox requires a filesystem that allows the use of user-specified extended attributes. Run getfattr * in the Dropbox directory: you'll see that all the files have an extended attribute, named either user.com.dropbox.attrs or user.com.dropbox.attributes depending on Dropbox version.

To allow the use of extended attributes, you can either add the user_xattr mount option to /etc/fstab for your /dev/sda1, or (more convenient for external drives) you can add the option to the filesystem itself with tune2fs -o +user_xattr /dev/sda1. You should probably unmount the filesystem for making this modification: it will take effect the next time you mount it.

Here is a more definitive list of the requirements of modern Dropbox on Linux.