Synology NAS Backups with Minimal Bus Factor


If you're wanting to backup your Synology NAS, you probably just want to use one of their off-the-shelf solutions in their Package Center. However, if you're stubborn like me and want to use the same CLI tool you use elsewhere, this post is for you. I'll describe how to use restic to backup folders you care about on your Synology NAS to an external hard drive and S3 conformant cloud storage providers that are supported by restic and one supported by rclone. If you want to use another command line tool, much of the instructions I provide here should still be applicable.


Raid redundancy is not a backup

Hard drives installed in a NAS run under the same conditions, workloads, and are often the same brand and bought at the same time. For those reasons, multi-drive failure is a real possibility. Not to mention, fire, flood, theft, and other disasters.

Not caring until it's gone

I lost some videos I recorded of myself playing videos games a long time ago that I very much wish I still had for nostalgia. At the time I ran 2 10k RPM WD Raptors in RAID 0 in the early 2000s — not thinking about doubling the risk of data loss. Of course, one of the drives failed, and I had no backups.

I have been "backing up" since then, but not until I read about 3-2-1 Backup Rule, did I realize I need to up my game.

My imperfect backup solution

I really only have ~90GB of data that I never want to lose — Family photos, videos, docs etc. — out of several terabytes of data I wouldn't lose sleep over. Or put another way, I only want to pay for what I need. However, there's no reason this won't scale to terabytes of data. The only limiting factor is your upload speed and patience.

I ditched Dropbox for Syncthing and use that to keep a bunch of things in sync across many devices. I like to tell myself this is enough redundancy until I perform a manual backup — famous last words.

Once a year I offload from the syncthing folders to encrypted folders on the NAS. Some of these folders fall into the "don't want to lose" category. Then I perform a manually backup using restic to an external hard drive and a few cloud providers. Multiple cloud providers is my own compensation for the lack of not using a real 2nd media type as 3-2-1 suggests. I put one of the cloud backups in a region on the other side of the planet just in case a Carrington like event or even 100X worse happens. Not saying I think that will cause massive data loss, but it's fun to be paranoid.

Restic snapshots are encrypted with a password. Of course, I generate long complex passwords for each backup destination. Therefore, I'm not concerned about if the cloud provider supports encryption at rest or E2E encryption.

Backing up passwords and encryption keys

All these redundant backups are only as good as storage of secrets.

I use gopass to manage my passwords which is a derivative of pass. In short, the passwords are encrypted and stored in a git repo. I have this repo on multiple devices so I get the distributed redundancy from git. I could improve this by having auto sync to another git forge provider though.

The Android app works better than you'd expect from a less popular password manager. However, bootstrapping things with GPG keys is a huge pain compared to other password managers. I used to sync a KeePass database with Syncthing.

I haven't got my wife to switch from KeePass yet. Definitely, a trade-off in complexity. Complex to setup, but easier to use and manage. I love using Emacs to manage my passwords. I haven't looked into it much, but I wish I could easily sync between gopass and something like Bitwarden for the best of both worlds.

Bus factor of 1

So what if I get hit by a bus? Can my significant other figure out this convoluted mess? This is a real concern. Documenting my backup strategy is a start.

What if I cancel my credit card and forget to update the payment method for the cloud providers? I don't know. I just checked and the providers I choose don't have a way to add a backup payment method. So I guess I'll just use different credit cards for the 2nd paid providers I'm using and hope for the best.

The intersection of security, redundancy, and not getting locked in by proprietary tools makes the bus factor hard problem to solve.

Cloud providers and costs

I've been using Storj and Backblaze B2 since 2021. I picked Storj because the first 150GB is free — more than I need for now, but not something I can depend on.

Last year, 2022, Backblaze B2 cost for me was $3.20 for the year. About $0.27 per month after tax.

This year I added Wasabi because of it's S3 conformance, the backup steps are nearly exactly the same, and low cost. - edit (2023-08-12) actually after some time using the service I found it to be much more expensive than Blackblaze B2 ~$6 / month. So I wouldn't recommend it if your use case is similar to mine.


External Hard Drive

On Ebay, in late 2021, I bought a:

  • ~$55 WD My Passport 4TB Certified Refurbished Portable Hard Drive.

Since using the space doesn't incur any additional cost like cloud storage, I backup more than just the "don't want to lose" category.

Synology Diskstation

  • Model: DS918+
  • Software Version: 7.1.1-42962 Update 4
  • RAM: 16GB
  • CPU: INTEL Celeron J3455
  • HDD: 4x HGST Deskstar NAS 6TB 7200 RPM

Synology is not for terminal junkies

I bought a Synology NAS because at the time I didn't want to roll my own. Trying to do things in the terminal on a Synology NAS is a PITA for reasons that will become clear shortly. I will definitely be rolling my own in the future.


Install Docker

Docker is why this process is more of a pain than it should be. In 2021, I was able to ssh into my NAS and install the nix package manager and then install restic.

It's not clear to me why I no longer have nix. Perhaps an update blew it away? And I'm no longer able to install it. Both the official and unofficial installers fail at least for me at the time of writing.

Synology's distribution of Linux doesn't appear to have any other package managers available, but we can fall back on Docker.

Installing Docker should be easy enough through the Package Center.

Enable SSH

If you follow the instructions on the Synology website, you should be able to ssh into your NAS with an admin account.

For me this looks like:

ssh will@nas -p 6666

In a strange act of security through obscurity, I didn't use the standard port 22 for SSH.

Set TERM if needed

If echo $TERM is not one of the following values, such as xterm, then your probably going to have issues with the terminal (such as backspace not working).

root@NAS:~# find /usr/share/terminfo/ -type f

If you find yourself unable to backspace, ctrl-C to intreupt the command and then run:




And that will probably fix it.

I use alacritty and many servers I SSH into don't have terminfo for it. Setting the TERM variable to xterm-256color prepended to ssh is another way to get around this. However, I'm not sure if this works from Windows. For example:

TERM=xterm-256color ssh will@nas -p 6666


Most of the examples from now on assume you are logged in as root.

I will use root@NAS:~# to denote commands run as root.

Login with root with the same password as your admin account:

sudo -i

Fix bash history

Or expect to lose it.

root@NAS:~# echo $HISTFILE
root@NAS:~# echo $HISTSIZE
root@NAS:~# echo $HISTFILESIZE

Ha! I wish I checked these variables earlier. No! Instead I lost my bash history, and then increased the history size. Lost it again and realized the history file was in a tmp directory.

Increase your history size and set the history file to a permanent location:

root@NAS:~# echo "export HISTSIZE=10000" >> ~/.bashrc
root@NAS:~# echo "export HISTFILESIZE=10000" >> ~/.bashrc
root@NAS:~# echo "export HISTFILE=/root/.bash_history" >> ~/.bashrc

Format external hard drive

Ok, so I formatted my external hard drive from my desktop in Linux. I wasn't thinking about making a blog post at the time. It should be doable from the Synology. For me, fdisk and mkfs.ext4 are available, but not lsblk.

I'm going to do my best to estimate the steps for formatting an external hard as root on a Synology NAS, but there's good chance I'm missing something:

Plug in the drive and print out the list of devices using fdisk -l:

For me I see /dev/sdq is my external hard drive:

Disk /dev/sdq: 3.7 TiB, 4000752599040 bytes, 7813969920 sectors
Disk model: My Passport 25E2

I can also see that it's auto-mounts to /volumeUSB1/usbshare:

root@NAS:~# cat /proc/mounts | grep -i sdq
/dev/sdq /volumeUSB1/usbshare ext4 rw,relatime,nodelalloc,synoacl,data=ordered 0 0

If your external hard drive doesn't have a filesystem yet, then it probably won't auto-mount.

Unmount the external hard drive if needed:

root@NAS:~# umount /volumeUSB1/usbshare/

Wipe the filesystem and create a new ext4:

root@NAS:~# wipefs -a /dev/sdx
root@NAS:~# mkfs.ext4 /dev/sdx

Replace sdx above with your device name.

You should now be able to unplug and plug it back in for to auto-mount to /volumeUSB1/usbshare or something similar.

Docker basics

Let's start with passing --help to restic:

docker run -it --rm restic/restic --help

Here's a ChatGPT breakdown of the command:

This command is used to run a Docker container with the restic/restic image, which is an open-source backup program. Let's break down the command and its components:

  1. docker run: This is the primary command to run a new container from a Docker image.

  2. -it: This is a combination of two flags:

    • -i (interactive): Keeps the standard input (stdin) open to interact with the container.

    • -t (tty): Allocates a pseudo-TTY (terminal) to the container, allowing you to interact with the container as if it were a standard terminal.

  3. --rm: This flag removes the container automatically when it exits. This is useful for keeping your system clean and avoiding unnecessary container accumulation.

  4. restic/restic: This is the name of the Docker image that the container will be based on. In this case, it's the official Restic backup program's image.

  5. --help: This is an argument passed to the Restic program inside the container. It tells Restic to display its help message, which contains information about the available commands and options.

This is a good starting point for understanding what's going on in the rest of the blog post. I'll often break long commands across multiple lines using \ at the end of the line. Usually I edit these commands outside of the shell and paste them in with ctrl-shift-v.

Let's backup!

Things to note

For me Synology has all my data under /volume1.

And the root mount / has very little space:

root@NAS:~# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/md0                2.3G  1.8G  431M  81% /

In fact, not enough for what restic is going to need for cache: ~/.cache/restic/

Therefore, to avoid running out of cache space, I use the --cache-dir to change the cache directory to a place that has much more space available.

The commands I give below are mostly self-contained. However, note that one could just change the entrypoint of the container to sh

root@NAS:~# docker run -it --rm \
  -v /volume1:/volume1 \
  --entrypoint /bin/sh \

And then you're in a shell inside the container where you can run restic commands directly.

External hard drive

Initialize the restic repository if not done yet.

root@NAS:~# docker run -it --rm \
  -v /volumeUSB1/usbshare:/usbshare \
  restic/restic \
  -r /usbshare/restic-backups/ \

It will prompt you for a password to encrypt the repo. Make sure you keep it safe.

Note that -v /volumeUSB1/usbshare:/usbshare mounts the external hard drive volume to /usbshare inside the container.

The restic repo is now initialized at /volumeUSB1/usbshare/restic-backups/ (outside the container).

And backup:

root@NAS:~# docker run -it --rm \
  -v /volume1:/volume1 \
  -v /volumeUSB1/usbshare:/usbshare \
  restic/restic \
  -r /usbshare/restic-backups/ \
  --cache-dir /volume1/.cache/restic/ \
  --verbose \
  backup \
  /volume1/backup-safe/ \
  /volume1/backup/ \
  /volume1/games/ \
  /volume1/music/ \
  /volume1/photo/ \

Replace /volume1/* folders with what you want to backup.

Again note that I am mounting /volume1 to /volume1 inside the container.

Backblaze B2

Also see:

Initialize the restic repository if not done yet:

root@NAS:~# docker run -it --rm \
  restic/restic \
  -r b2:<B2-BUCKET-NAME>:restic-backups/ \

Note -e is a way to pass environment variables to the container.


root@NAS:~# docker run -it --rm \
  -v /volume1:/volume1 \
  restic/restic \
  -r b2:<B2-BUCKET-NAME>:restic-backups/ \
  --cache-dir /volume1/.cache/restic/ \
  --verbose \
  backup \
  /volume1/backup-safe/ \



I no longer use Wasabi due to higher costs, but I'll leave this here incase you want to use it.

Also see:

Initialize the restic repository if not done yet:

root@NAS:~# docker run -it --rm \
  restic/restic \

Note -e is a way to pass environment variables to the container.


root@NAS:~# docker run -it --rm \
  -v /volume1:/volume1 \
  restic/restic \
  --cache-dir /volume1/.cache/restic/ \
  --verbose \
  backup \
  /volume1/backup-safe/ \

Replace /volume1/* folders with what you want to backup.


Ok fair warning, this is more involved than the other ones. In fact I almost gave up this year and it was part of the reason I looked into another paid storage provider. On top of that, I failed to write down the steps as I did them, so I'm going to estimate again from memory. Here is the documentation I followed:

I'm using their "S3 compatible hosted gateway" integration pattern to minimize upload.

They offer end-to-end encryption, but I opted for server-side encryption because the data that I'm backing up there is already encrypted using restic.

This is going to require two tools rclone and restic.

So I used the restic docker image and changed the entrypoint to sh.

root@NAS:~# docker run -it --rm \
  -v /volume1:/volume1 \
  --entrypoint /bin/sh \

Once you're inside the running container, you can use the apk package manager to install rclone:

apk add rclone

Using this documentation above, perform rclone config and follow the steps in the docs.

Once complete, Use the mkdir command to create new bucket, e.g. mybucket.

rclone mkdir storj:mybucket

Again, still in the container, perform the backup:

restic -r rclone:storj:<STORJ-BUCKET-NAME>/restic-backups \
  --cache-dir /volume1/.cache/restic/ \
  --verbose \
  backup \
  --pack-size=60 \
  /volume1/backup-safe/ \

Replace /volume1/* folders with what you want to backup.

Restore from External HDD Backup

Ok this will be incomplete. I'll try to update this next year when I do backups again.

This year I was doing my taxes and had a bit of a fire drill when I couldn't find any previous years. I later realized I simply accidentally dragged them into a random folder using Synology's web UI.

Here are some rough steps it took to mount the backup and be able to view the files from Linux:

$ lsblk # find the device name of the external HDD
$ sudo mkdir /mnt/media
$ sudo mount -t ext4 -o ro /dev/sdx /mnt/media
$ sudo restic -r /mnt/media/restic-backups/ mount ~/backup-mount \
  --allow-other --no-default-permissions
$ cd ~/backup-mount && ls -lah # view files
$ sudo umount /mnt/media # unmount when done.


It's worth noting you should search and delete passwords and keys from your history when done. Since most of everything was done in Docker, there shouldn't be much to clean up.

You can find your history file with echo $HISTFILE.