Unison is a nice tool to synchronize file-system. It has the advantage of running on many different platforms, use an ssh connection and be good at one thing (file synchronization). I’m using it to synchronize my data between my laptop and a Unix server that acts as a back-up. I wanted to use it also to have a mirror of all my data on my NAS, in particular my music that is then served on my home network from the NAS. Until now I used so rsync scripts to do the trick, but rsync is quite stupid with permissions and cannot detect file moves. The main advantage of rsync is that it is already installed on any Linux machine, including my NAS.

Here are the steps to follow to install unison on a Synology DS 207 NAS:

1. Enable ssh access
2. Download the ipkg bootstrap script ds101-bootstrap_1.0-4_powerpc.xsh (the DS 101 and the DS 207 have the same processor, so this is OK).
3. Copy the file to the NAS, for instance in the path /volume1/tmp.
4. Ssh into your NAS as user root (ssh root@xxx.local).
5. Go to the directory (cd /volume1/tmp)
6. Execute the installation script: ds101-bootstrap_1.0-4_powerpc.xsh
7. If there is an error about a missing dependency for wget-ssl, don’t sweat it, it still works.
8. To check that it works, try to update the package list ipkg update
9. Download the package definition for unison: unison_22757-1_powerpc.ipk. You can do this directly from the NAS or from your computer, and then copy the file to the /volume1/tmp directory.
10. Install the unison package: ipkg /volume1/tmp/unison_22757-1_powerpc.ipk.