Module 8 · 8.1

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Backups: who does what, and the 3-2-1 rule

Module 8: Backups, exit and management · Reading time: 11 minutes

Learning objective: After this lesson, you can explain what your cloud service does and doesn't restore for you, why synchronising isn't a backup, and set up your own backup following the 3-2-1 rule that you've actually tested yourself.

Key concepts: backup, shared responsibility, trash bin, versions, the provider's system backup, your own backup, 3-2-1 rule, offline or disconnected copy, ransomware, synchronisation, restore test, retention period, recovery point objective (how much work you can afford to lose)

"But it's in the cloud, isn't it?"

That's the sentence you hear most often, and it's only half true. A cloud service makes sure your files don't disappear if a hard drive in the data centre breaks down. That's a different thing from: restoring everything that you, a colleague, or a virus has deleted or messed up.

At Bakkerij De Korrel, the following happens. On Friday afternoon, an employee opens an infected attachment. Ransomware encrypts the files on his laptop, including those in the synced folder. The sync app duly does its job and uploads the encrypted versions to the cloud within a few minutes, and from there to his colleagues' laptops. On Monday morning, nobody can open the recipes anymore.

Whether the service can help you then depends on three things: the versions, the trash bin, and what the provider itself keeps. And whether you have your own copy that the ransomware couldn't reach.

Synchronising is not a backup

A synchronisation keeps locations identical. That's exactly what you don't want when something goes wrong: a deleted file gets deleted everywhere, an encrypted file gets encrypted everywhere. A backup is a copy from an earlier moment, which doesn't automatically follow what's happening now.

What your cloud does have:

Versions: with every change, the service keeps the old version for a while. After the ransomware, you restore Friday morning's version.
Trash bin: deleted files stay around for a while.

But both have limits. They get cleared out after a period (often around 30 days), sometimes sooner if space is needed, and they live in the same account. Anyone who takes over your account, or accidentally empties the trash bin, also removes your safety net.

Shared responsibility: who does what?

With every cloud service, responsibility is divided. Ask your provider about it, and put it in writing.

What	Who	Example
Hardware and data centre	Provider	You don't notice a faulty disk
System backup of the servers	Provider	After a disaster, such as a broken server, the provider restores the system. Often you can't retrieve anything from this yourself
Day-to-day file recovery	You, using versions and the trash bin	A file accidentally overwritten
Your own backup outside the service	You	Lost account, provider goes bankrupt, ransomware that also hits the versions, retention periods longer than the service offers
Mail backup	Varies by provider	With some providers you can restore a mailbox yourself from an overnight backup, with others you can't

Ask specifically: how long do you keep versions and the trash bin? Do you make your own backups, and can I have something restored from them? How long? Where are they stored (different data centre, same country)? What does a restore cost, and how fast is it? What happens to my data if I cancel?

The 3-2-1 rule

For your own backup, the 3-2-1 rule is the best-known guideline. The Dutch National Cyber Security Centre (NCSC) explains it like this:

3 copies of your important data: the original and two backups;
on 2 different types of storage, for example the cloud and an external drive;
of which 1 is kept in a different location.

For ransomware there's an important addition: at least one copy must be disconnected or unchangeable, so a virus on your computer can't reach it. An external drive that's always plugged into the laptop therefore doesn't count as a safe copy.

For De Korrel, that looks like this:

Copy	Where	How often
1. Original	The new European cloud, with versions and trash bin	Always
2. Own backup	A second, separate backup service or storage with a different provider, with its own login and its own retention period	Every night, automatically
3. Offline copy	Two external drives that take turns going home with the owner	Every Monday, by hand

Important for the GDPR: your backups also contain personal data. A backup with another service is also a form of processing, requiring a data processing agreement (DPA) (lesson 9.2), and an external drive should be encrypted.

How much work can you afford to lose, and how fast does it need to come back?

Two questions determine how robust your backup needs to be:

How much work can you afford to lose? If you make a backup once a night and something goes wrong at 4pm, you've lost a day's work. For recipes, that's manageable; for a webshop with orders, it isn't.
How fast does it need to come back? A few folders can be restored in an hour. Downloading and restoring a complete environment of hundreds of gigabytes can take days. Know that in advance.

A backup you haven't tested is just a pile of data

The NCSC says it too: testing is at least as important as making the backup. Many organisations only discover during a disaster that the backup hadn't run for months, or that the password for the encrypted backup was held by a former colleague.

So plan a restore test (exercise E8.1):

Choose a folder, a calendar, and a mailbox.
Restore them from the backup to a separate location (never over the original).
Open a few files and check the date and content.
Note how long it took and what went wrong.
Repeat this at least once a year, and after every change to the backup.

In practice: what this looks like with a provider

In a WebOké Nextcloud, you restore files yourself from Deleted files and restore older versions yourself. Deleted files and versions are kept for up to 31 days, and removed sooner if together they use more than half of your free space. A version you give a name to is kept permanently. WebOké also makes system backups of the servers, as a safeguard against disasters; as a customer, you can't restore anything from these yourself. For your own copy, the manual recommends including the desktop app's folder in your computer's backup, or occasionally copying it to an external drive.

For hosting packages and mail packages, WebOké has a different setup: every night a backup of the entire package, including mailboxes, which you can restore or download yourself for 30 days via WebOké Backups in My WebOké.

With other providers, this varies a lot. So always ask: the fact that "backups" exist doesn't mean you can restore anything from them yourself.

Summary

Synchronising is not a backup: mistakes and ransomware get synced just as readily.
Versions and the trash bin are your daily safety net, with a limited retention period and within the same account.
Record what the provider does and what you do. The provider's system backup is usually not meant for your day-to-day recovery.
Follow the 3-2-1 rule, with at least one disconnected copy.
Test your restore at least once a year, to a separate location.

Quiz

Exercise

Exercise E8.1: Backup agreements and a restore test. Fill in the "who does what" table for your new service (ask your provider about it), design your own 3-2-1 setup, and carry out a restore test following the protocol in OPDRACHTEN.md.

Exercise E8.1: Backup agreements and a restore test

Ask the provider about their backup arrangements, fill in the tables, and do the restore test following the protocol from the lesson.

Chosen and counted beforehand: a folder with at least 20 files, one calendar, one mailbox or mail folder, and two spot checks.
Start time noted.
Restored from your own backup to a separate location (never over the original).
Numbers and size compared, spot checks opened.
End time and restore time noted.
Test location cleaned up.
Next test scheduled in the calendar (within 12 months at the latest).

Who does what (per part, files, calendar, contacts, mail, chat): versions, recycle bin, the provider's system backup, your own backup.

Your 3-2-1 setup: copy 1, 2 and 3 (where, type of storage, disconnected, how often), encrypted, data processing agreement.

How much work can you afford to lose at most (hours), and how quickly does the most important part need to work again (hours)?

After the test: numbers before and after, restore time, what went wrong, what will you change?

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