The times they are a-changin’. This post seems to be older than 2 years—a long time on the internet. It might be outdated.

Having a backup of your data is important, and for me it’s taken several different forms over the years — morphing as my needs have changed, as I’ve gotten better at doing backups, and as my curiosity has compelled me.

For various reasons that will become clear, I’ve iterated through yet another backup system/strategy which I think would be useful to share.

The Backup System That Was

The most recently incarnation of my backup strategy was centered around CrashPlan and looked something like this:

Atlas is my NAS and where a bulk of the data I care about is located. It backs up its data to CrashPlan Cloud.

Andrew and Rachel are the laptops we have. I also care about that data and they also backup to CrashPlan Cloud. Additionally, they also backup to Atlas using CrashPlan’s handy peer-to-peer system.

Brother and Mom are extended family member’s laptops that just backup to CrashPlan Cloud

Fremont is the web server (decommissioned recently though), it used to backup to CrashPlan as well.



This all worked great because CrashPlan offered a (frankly) unbelievably good CrashPlan+ Family Plan deal that allowed up ten computers and “unlimited” data — which CrashPlan took to mean somewhere around 20TB of total backups1 — for $150/year. In terms of pure data storage cost this was $0.000625/GB/month2, which is an order of magnitude less than Amazon Glacier’s cost of $0.004/GB/month3.

And then one year ago CrashPlan announced:



we have shifted our business strategy to focus on the enterprise and small business segments. This means that over the next 14 months we will be exiting the consumer market and you must choose another option for data backup before your subscription expires. …

To allow you time to transition to a new backup solution, we’ve extended your subscription (at no cost to you) by 60 days. Your new subscription expiration date is 09/28/2018.



Important Things In A Backup System

3-2-1-Bang

First a quick refresher on how to backup. Arguably the best method is the 3-2-1-bang strategy: “three total copies of your data of which two are local but on different mediums (read: devices), and at least one copy offsite.” Bang represents inevitable scenario where you have to use your backup.

This can be as simple as backing up your computer to two external hard drives — one you keep at home and backup to weekly and one you leave at a friends house and backup to monthly.

Of course, it can also be more complex.

Considerations

Replacing CrashPlan was hard because it has so many features for its price point, especially:

Encryption

Snapshots

Deduplication

Incremental backup

Recentness

…these would become my core requirements, in addition to also needing to understand how the backup software works (because of this I strongly prefer open-source).

I also had additional considerations I needed to keep in mind:

How much data I needed to backup: Atlas: While I have 12TB of usable space (of which I’m using 10TB), I only had about 7TB of data to backup. My Laptop: < 1TB GB Wife’s Laptop: < 0.250 TB Extended family: <500 GB each Fremont: decommissioned in 2017, but < 20 GB at the time

How recent I wanted the backups to be (put another way, how much time/effort was I willing to loose):

I was willing to lose up to one hour of data

What kind of disasters was I looking to mitigate: Hyper localized incident (e.g. hard drive failure, stupidity, file corruption, theft, etc) This could impact a single device Localized incident (e.g. fire, burglary, etc) This could impact all devices within a given structure ( < ~ 1000 m radius) Regionalized incident (e.g. earthquake, flood, etc) This could impact all devices in the region (~ 1000 km radius)

How much touch-time did I want to put in to maintain the system: As little as possible (< 10 hours/year)



The New Backup System

There’s no single key to the system and this is probably the way it should be. Instead, it’s a series of smaller, modular elements that work together and can be replaced as needed.

My biggest concern was cost, and the primary driver for cost was going to be where to store the backups.



Where to put the data?

I did look at off-the-shelf options and my first consideration was just staying with CrashPlan and moving to their Small Business plan, but at $120/device/year I was looking at $360/year just to backup Atlas, Andrew, and Rachel.

Carbonite, a CrashPlan competitor but also who CrashPlan has partnered with to transition their home users to, has a “Safe” plan for $72/device/year, but it was a non-starter because they don’t support Linux, have a 30 day limit on file restoration, and do silly things like not automatically backing up files over 4GB and not backing up video files.



Backblaze is The Wirecutter’s Best Pick comes in at $50/device/year for unlimited data with no weird file restrictions, but there’s some wonkiness about file permissions and time stamps, and it also only retains old file versions/deleted files for 30 days.

I decided I could live with Backblaze Backups to handle the off-site copies for the laptops, at least for now. I was back to the drawing board for Atlas though.



The most challenging part was how to create a cost-effective solution for highly-recent off-site data backup. I looked at various cloud storage options4, setting up a server at a friends house (high initial costs, hands-on maintenance would be challenging, not enough bandwidth), and using external hard drives (recentness would be too prolonged in backups).

I was dreading how much data I had as it looked like backing up to the cloud was going to be the only viable option, even if it was expensive.

In an attempt to reduce my overall amount of data hoarding, I looked at the different kinds of data I had and noticed that only a relatively small amount changed on a regular basis — 2.20% within the last year, and 4.70% within the last three years.

The majority5 was “archive data” that I still want to have immediate (read-only) access to, but was not going to change, either because they are the digital originals (e.g. DV, RAW, PDF) or other files I keep for historic reasons — by the way, if I’ve ever worked on a project for you and you want a copy because you lost yours there’s a good chance I still have it.

Since archive data wasn’t changing, recentness would not be an issue and I could easily store external hard drives offsite. The significantly smaller amount of active data I could now backup in the cloud for a reasonable cost.

Backblazes B2 has the lowest overall costs for cloud storage: $0.005/GB/month with a retrieval fee of $0.01/GB6.

Assuming I’m only backing up the active data (~300GB) and I have a 20% data change rate over a year (i.e. 20% of the data will change over the year which I will also need to backup) results in roughly $21.60/year worth of costs. Combined with two external WD 8TB hard drives for rotating through off-site storage and the back-of-the-envelope calculations were now in the ballpark of just $85/year when amortized over five years.

How to put the data?

I looked at, tested, and eventually passed on several different programs:

borg/attic…requires server-side software

duplicity…does not deduplicate

Arq…does not have a Linux version

duplicacy…doesn’t support restoring files directly to a directory outside of the repository7

To be clear: these are all very good programs and in another scenario I would likely use one of them.

Also, deduplication was probably the biggest issue for me, not so much because I thought I had a lot of files that were identical (or even parts of files) — I don’t — but because I knew I was going to be re-organizing lots of files and when you move a file to a different folder the backup program (without deduplication capability) doesn’t know that it’s the same file8.

I eventually settled on Duplicati — not to be confused with duplicity or duplicacy — because it ticks all right boxes for me:

open source (with a good track record and actively maintained)

client side (e.g. does not require a server-side software)

incremental

block-level deduplication

snapshots

deletion

supports B2 and local storage destinations

multiple retention policies

encryption (including ability to use asymmetric keys with GPG!)

Fortunately, OpenMediaVault (OMV) supports Duplicati through the OMVExtras plugin, so installing and managing it was very easy.

The default settings appear to be pretty good and I didn’t change anything except for:

Adding SSL encryption for the web-based interface

Duplicati uses a web-based interface9 that is only designed to be used on the local computer — it’s not designed to be run on a server and have then access the GUI remotely through a browser. Because it was only designed to be accessed from localhost, it sends passwords in the clear, which is a concern but one that has already been filed as an issue and can be mitigated with using HTTPS.

Unfortunately, the OMV Duplicati plugin doesn’t support enabling HTTPS as one of its options.

Fortunately, I’m working on a patch to fix that: https://github.com/fergbrain/openmediavault-duplicati/tree/ssl

Somewhat frustratingly, Duplicati requires using the PKCS 12 certificate format. Thus I did have to repackage Atlas’ SSL key:

openssl pkcs12 -export -out certificate.pfx -inkey private_key.key -in server_certifcate.crt -certfile CAChain.crt

Asymmetric keys

Normally Duplicati uses symmetric keys. However, when doing some testing with duplicity I was turned on to the idea of using asymmetric keys.



If you generated the GPG key on your server then you’re all set. However, if you generated them elsewhere you’ll need to move over to the server and then import them:



gpg --import private.key gpg --edit-key {KEY} trust quit # enter 5<RETURN> # enter y<RETURN>

Once you have your GPG key on the server you can then configure Duplicati to use them. This is not intuitive but has been documented:

--encryption-module=gpg --gpg-encryption-command=--encrypt --gpg-encryption-switches=--recipient "andrew@example.com" --gpg-decryption-command=--decrypt --passphrase=unused

Note: the recipient can either be an email address (e.g. andrew@example.com) or it can be a GPG Key ID (e.g. 9C7F1D46).

The last piece of the puzzle was how to manage my local backups for the laptops. I’m currently using Arq and TimeMachine to make nightly backups to Atlas on a trial basis.

Final Result

The resulting setup actually ends up being very similar to what I had with CrashPlan, with the exception of adding two rotating external drives which brings me into compliance with the “3 total copies” rule — something that was lacking.

Each external hard drive will spend a year off-site (as the off-site copy) and then a year on-site where it will serve as the “second” copy of the data (first is the “live” version, second is the on-site backup, and third is the the off-site backup).

Overall, this system should be usable for at the least the next five years — at least in terms of data capacity and wear/tear. Total costs should be under $285/year. However, I’m going to work on getting that down even more over the next year by looking at alternatives to the relatively high per-device cost for Backblaze Backup which only makes sense if a device is backing up close to 1TB of data — which I’m not.

Update : Edits based on feedback

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