Installing MergerFS on a Synology NAS

Originally from Reddit. Copied and edited with permission.

A different version to overcome some problems with the method below, can be found here

Install Entware

1. SSH into your NAS and switch to the root user:

sudo su

2. Create a folder on your hdd (outside rootfs):

mkdir -p /volume1/@Entware/opt

2. Remove /opt and mount optware folder.

Make sure that /opt folder is empty (Optware is not installed), we will remove the /opt folder with its contents at this step.

rm -rf /opt
mkdir /opt
mount -o bind "/volume1/@Entware/opt" /opt

3. Run install script depending on the processor. Use command uname -m to find out. Then run the corresponding command.

armv8 (aarch64) - Realtek RTD129x

wget -O - http://bin.entware.net/aarch64-k3.10/installer/generic.sh | /bin/sh

armv5

wget -O - http://bin.entware.net/armv5sf-k3.2/installer/generic.sh | /bin/sh

armv7

wget -O - http://bin.entware.net/armv7sf-k3.2/installer/generic.sh | /bin/sh

x64

wget -O - http://bin.entware.net/x64-k3.2/installer/generic.sh | /bin/sh

4. Create an Autostart Task On Synology

Create a triggered user-defined task in Task Scheduler.

• Go to: DSM > Control Panel > Task Scheduler
• Create > Triggered Task > User Defined Script
  • General
  • Task: Entware
  • User: root
  • Event: Boot-up
  • Pretask: none
• Task Settings
  • Run Command: Paste the below script in.

#!/bin/sh

# Mount/Start Entware
mkdir -p /opt
mount -o bind "/volume1/@Entware/opt" /opt
/opt/etc/init.d/rc.unslung start

# Add Entware Profile in Global Profile
if grep  -qF  '/opt/etc/profile' /etc/profile; then
	echo "Confirmed: Entware Profile in Global Profile"
else
	echo "Adding: Entware Profile in Global Profile"
cat >> /etc/profile <<"EOF"

# Load Entware Profile
[ -r "/opt/etc/profile" ] && . /opt/etc/profile
EOF
fi

# Update Entware List
/opt/bin/opkg update

5. Reboot your NAS.

6. SSH back into your NAS

7. Install mergerfs by the following command.

sudo opkg install mergerfs

9. Make sure it's installed by running the following command. Mergerfs binary is expected to be listed there.

sudo ls /volume1/@Entware/opt/bin 

This should print the usage helper of mergerfs.

mergerfs --help

10. If you want the latest build of mergerfs, you can download the mergerfs-static-linux_$ARCH.tar.gz from Github releases page, remember to replace $ARCH with your architecture, e.g. what uname -m tells you.

Extract the .tar.gz archive and use its content to update the mergerfs and mergerfs-fusermount binaries in /opt/bin/

11. Configure mergerfs. Note: Change the file paths to your setup.

*MY CONFIG IS (Don't know if it is the perfect setting, but works in my testing) *

mergerfs -o rw,use_ino,allow_other,func.getattr=newest,category.action=all,category.create=ff,dropcacheonclose=true /volume1/Media/TempMedia:/volume1/Media/GMedia /volume1/Media/FinalMedia 

If mergerfs complains about existing files because the destination already has the Synology @eaDir directory, you can use the option nonempty.

12. Create an Autostart Task On Synology for Mergerfs

• Go to: DSM > Control Panel > Task Scheduler
• Create > Triggered Task > User Defined Script
  • General
  • Task: Mergerfs
  • User: root
  • Event: Boot-up
  • Pretask: Entware
• Task Settings
  • Run Command: Paste the below script in.

#!/bin/sh

/opt/bin/mergerfs -o rw,use_ino,allow_other,func.getattr=newest,category.action=all,category.create=ff,dropcacheonclose=true /volume1/Media/TempMedia:/volume1/Media/GMedia /volume1/Media/FinalMedia 

13. Profit