Evaggelos Balaskas - System Engineer

I am only using btrfs for the last few years, without any problem. Drobox’s decision is based on supporting Extended file attributes and even so btrfs supports extended attributes, seems you will get this error:

I have the benefit of using encrypted disks via LUKS so in this blog post, I will only present a way to have an virtual disk with ext4, to your dropbox folder on-top of your btrfs!

Allocating disk space

Let’s say that your have 2G of dropbox space, allocate 2G of file size:

fallocate -l 2G Dropbox.img

you can verify the disk image by:

qemu-img info Dropbox.img

image: Dropbox.img
file format: raw
virtual size: 2.0G (2147483648 bytes)
disk size: 2.0G

Map Virtual Disk to Loop Device

Then map your virtual disk to a loop device:

sudo losetup `sudo losetup -f` Dropbox.img

verify it:

losetup -a

/dev/loop0: []: (/home/ebal/Dropbox.img)

then loop0 it is.

Create an ext4 filesystem

sudo mkfs.ext4 -L Dropbox /dev/loop0

Creating filesystem with 524288 4k blocks and 131072 inodes
Filesystem UUID: 09c7eb41-b5f3-4c58-8965-5e366ddf4d97
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

Move Dropbox folder

You have to move your previous dropbox folder to another location. Dont forget to cloase dropbox-client and any other application that is using files from this folder.

mv Dropbox Dropbox.bak

renamed 'Dropbox' -> 'Dropbox.bak'

and then create a new Dropbox folder:

mkdir -pv Dropbox/

mkdir: created directory 'Dropbox/'

Mount the ext4 filesystem

sudo mount /dev/loop0 ~/Dropbox/

verify it:

df -h ~/Dropbox/

Filesystem      Size  Used Avail Use% Mounted on
/dev/loop0      2.0G  6.0M  1.8G   1% /home/ebal/Dropbox

and give the right perms:

sudo chown -R ebal:ebal ~/Dropbox/

Copy files

Now, copy the files from the old Dropbox folder to the new:

rsync -ravx Dropbox.bak/ Dropbox/

sent 464,823,778 bytes  received 13,563 bytes  309,891,560.67 bytes/sec
total size is 464,651,441  speedup is 1.00

and start dropbox-client

Four Step Process

$ sudo iptables -nvL | grep 8765

0    0    ACCEPT    tcp  --  *    *    192.168.0.0/24    0.0.0.0/0    tcp dpt:8765