Your Notes App Is Not a Backup: The 3-2-1 Rule for Notes

Delete a note on one device and a sync service deletes it on every device. Sync replicates the current state of your files — a deletion or corruption included — everywhere at once. A backup is the opposite: a separate, point-in-time copy you restore after something goes wrong. The 3-2-1 rule makes that copy trivial for plain files you own.

That distinction is not a MNMNOTE opinion. It comes straight from the people who do disaster recovery for a living. Backblaze, a backup company, states the failure mode plainly: "If your computer is hit with a ransomware attack and automatically synchronizes your data afterwards, all of your synced files will be corrupted." ¹ The U.S. Cybersecurity and Infrastructure Security Agency (CISA) says the same thing about any auto-copy that shares a fate with the original: "Rolling backups can silently propagate any corruption or malware in the primary files to the backup files." ² Your notes are just text. The rule that protects everyone else's data protects yours too.

Is sync the same as a backup?

No. Sync keeps multiple devices showing the same current version of a file. A backup keeps a separate copy of a past version that survives when the current one is lost. The two solve different problems, and one cannot stand in for the other.

Backblaze, writing about cloud sync services, is blunt: "they are not a viable backup solution and relying on them to protect your data can lead to trouble." ¹ The reason is the deletion-propagation trap. "If you or someone you shared a file with deletes that file, you are at risk of losing it forever unless the sync service you're using has a version history feature. Sync services do not create a copy of your files for backup, and require additional setup to make sure you have some data protection enabled." ¹

Read that carveout carefully, because fairness matters here. Sync can protect you — but only if it retains version history long enough, and only as a supplement. Sync as your only copy is the failure. A real backup never inherits the deletion in the first place.

What is the 3-2-1 backup rule?

The 3-2-1 rule is the data-protection baseline: keep three copies of any important file, on two different kinds of media, with one copy stored offsite. It is medium-agnostic — it works for a server farm or a folder of Markdown notes — because it is about redundancy, not about any particular app.

The rule was coined by photographer Peter Krogh in The DAM Book: Digital Asset Management for Photographers (O'Reilly, 2009) ³. As one interview with Krogh puts it, "He didn't invent the idea of three copies and offsite backup, but he did distill it down to what we now refer to as the 3-2-1 rule." ⁴ CISA later canonized it for everyday computer users, spelling out each leg ²:

• 3 — "Keep 3 copies of any important file: 1 primary and 2 backups." ²
• 2 — "Keep the files on 2 different media types to protect against different types of hazards." ²
• 1 — "Store 1 copy offsite (e.g., outside your home or business facility)." ²

Backblaze restates the same shape in plain English: "It advises that you keep three copies of your data on two different media with one copy off-site." ⁵ One important honesty note: CISA and Krogh were writing about general data, not note apps. This post applies their rule to personal notes — a sound move, since CISA explicitly addresses home users, but the rule is theirs, not ours.

Why plain files make every leg trivial

When your notes are plain Markdown files on your own device, each leg of 3-2-1 becomes a one-line habit. You can copy a file you hold; you cannot copy a note locked inside a proprietary cloud store. Ownership of the file is the precondition that makes a real backup possible at all.

CISA opens its guidance with who this is for: "All computer users, from home users to professional information security officers, should back up the critical data they have on their desktops, laptops, servers, and even mobile devices to protect it from loss or corruption." ² That is you. The diagram below maps the rule onto a notes folder.

flowchart TD
    A["Your notes folder<br/>(plain Markdown files)"] --> B["Copy 1: primary<br/>the working folder"]
    A --> C["Copy 2: second medium<br/>external drive or<br/>a local version-control repo"]
    A --> D["Copy 3: offsite<br/>encrypted copy you<br/>store elsewhere"]
    D --> E["Restore test<br/>open a copy and read it"]
    E --> F["Verified backup<br/>(the '0' in 3-2-1-1-0)"]

Figure: The 3-2-1 rule mapped onto a folder of plain-text notes. The working folder is copy 1; a second medium such as an external drive or a local version-control repository is copy 2; an encrypted copy kept somewhere else is the offsite copy 3. The final step — opening a copy and confirming it reads — is the verification that turns three copies into a real backup.

To make each leg concrete: copy 1 is your working notes folder. Copy 2 lives on a different kind of medium — an external drive, or a local version-control repository that also gives you the past states. Copy 3 goes offsite as an encrypted copy you keep somewhere your house cannot lose in one event. Because the notes are files, any standard file-backup tool moves them; nothing is locked behind an export wizard.

What counts as two different media?

Two copies on the same hard drive are not two media — they share a single point of failure. The "2" leg exists "to protect against different types of hazards," in CISA's words, so the copies must fail for different reasons ². A dropped laptop and a corrupt write should never be able to take every copy at once.

In practice, media diversity for notes means mixing at least two of these: the internal disk you work on, a separate external drive, and a copy held somewhere geographically distant. The offsite copy doubles as both your "1" (offsite) and a third medium. The test is simple — name the single event that would destroy every copy. If you can name one, you do not yet have media diversity.

The five-minute version

Start small. A backup you set up in five minutes and never test is better than no backup, but only barely — so this version ends with the test, not the copy. Do these steps once, then repeat copies on a schedule you will actually keep.

1. Find the folder. Locate where your notes live as files on disk. If you cannot find files, you do not yet own copies — fix that first.
2. Copy 2 (second medium). Copy the whole folder to an external drive, or commit it to a local version-control repository.
3. Copy 3 (offsite). Put an encrypted copy somewhere outside your home — a different building, a trusted remote location.
4. Include the attachments. Back up the image and attachment folder too, not just the .md files — a portable note breaks the moment its picture is missing ⁶.
5. Test the restore. Open a file from a backup copy and confirm it reads. An untested backup is not a backup.

The thirty-minute version: automate and verify

The five-minute version proves the concept; the thirty-minute version makes it durable. The goal is that new copies happen without you remembering, and that you can prove a restore works. Veeam, a backup vendor, extends 3-2-1 into 3-2-1-1-0 for exactly this reason: "It adds one immutable copy, and results in zero recovery errors." ⁷

The two new digits matter for notes too. The extra 1 is an immutable copy — one that ransomware or a stray script cannot overwrite, because at least one copy must be "unreachable or unchangeable" for worst-case recovery ⁷. The 0 is zero recovery errors: "A backup only matters if you can count on it to restore when it's needed." ⁷

Three habits get you there:

• Schedule copy 2. Put the second-medium copy on a recurring schedule so it runs whether or not you remember it.
• Keep one copy you can't edit. Send the offsite copy somewhere append-only or write-protected, so a corruption in the primary cannot propagate into it.
• Schedule a restore test. Once a month, open a random file from each copy and read it. That is your "0."

Common mistakes

Most note-loss stories trace back to one of a handful of predictable errors. Each one feels like a backup while it is quietly failing, which is what makes them dangerous — you discover the gap only at the moment you need the copy that was never really there. Avoid these three and you have already beaten the median note-taker.

• Treating sync as your backup. Sync replicates the current state — deletions and corruption included — to every device ¹. It is convenience, not redundancy. Use it with retained version history, never as your only copy.
• Keeping all copies on one machine or one provider. Two copies on the same disk fail together: "Rolling backups can silently propagate any corruption or malware in the primary files to the backup files." ² Different media exist "to protect against different types of hazards." ²
• Never testing the restore. A copy you have never opened is a guess. The "0" in 3-2-1-1-0 is verification ⁷ — without it, you only believe you have a backup.

Backup is not version history, and not export

These three words get used interchangeably and protect against three different disasters. Naming them keeps you from buying one when you needed another. A backup survives the loss of a copy. Version history rolls back one copy to a past state. Export is the escape hatch when you leave a tool entirely.

A local version-control repository happens to give you two of these at once — a second copy (backup) and the past states of each file (version history) — but they remain distinct guarantees. If you want the roll-back-to-yesterday workflow specifically, that is its own discipline; we cover it in keeping a version history of notes you own. If your worry is an app shutting down or locking you in, the right drill is the export-before-you're-forced-out checklist, not a backup.

The through-line across all three: each only works on files you can actually hold. You cannot 3-2-1 a database silo you do not control, you cannot diff a revision window you only rent, and you cannot export what was never plain text. Plain Markdown on your own device is what makes every one of them possible.

How this works in MNMNOTE

MNMNOTE stores your notes as plain Markdown files on your own device, offline, with no account required. Because they are ordinary files, every leg of 3-2-1 is something you do to your own data with whatever tools you already trust — no special exporter, no vendor lock-in, no permission needed.

That is the whole architectural point: ownership of the file is the precondition for ownership of the backup. A proprietary cloud note store cannot be 3-2-1'd by you, because you never hold the copies. A folder of Markdown can be copied to a drive, versioned in a local repository, and mirrored to an encrypted offsite copy — by you, today, without asking anyone. The app is where you write; the files are what survive.

Frequently asked questions

Is sync the same as a backup?

No. Sync keeps every device showing the same current version of a file, so a deletion or corruption propagates everywhere. A backup is a separate, point-in-time copy that survives that loss. Backblaze, a backup company, says sync services "are not a viable backup solution." ¹ Sync helps only when paired with retained version history — never as your sole copy.

How do I back up my Markdown notes?

Because notes are plain files, any standard file-backup tool works. Apply 3-2-1: keep three copies, on two media types, with one offsite ². Copy the folder (including attachments) to an external drive or a local version-control repository, mirror an encrypted copy offsite, then open a file from a backup to confirm the restore works.

What is the 3-2-1 backup rule?

Keep 3 copies of any important file, on 2 different media types, with 1 copy stored offsite ². Photographer Peter Krogh coined it in The DAM Book (2009) ^{3 4}, and CISA later canonized it for everyday users ². It is medium-agnostic, so it applies to a folder of notes exactly as it does to enterprise data.

What is 3-2-1-1-0?

It is Veeam's extension of 3-2-1: the extra 1 adds one immutable copy that cannot be overwritten, and the 0 means zero recovery errors — a backup you have verified can actually restore ⁷. For notes, that means keeping one write-protected copy and testing a restore on a schedule, so you are sure the copy is real.

Will my synced notes be deleted everywhere if I delete one?

Usually, yes — that is what sync does. As Backblaze puts it, if a file is deleted "you are at risk of losing it forever unless the sync service you're using has a version history feature." ¹ A separate backup copy never receives the deletion, which is exactly why a backup is not the same thing as sync.

What is the difference between backup and version history?

A backup is a redundant copy that survives the total loss of another copy. Version history rolls a single copy back to an earlier state. A local version-control repository can provide both at once, but they are different guarantees — see our guide to version history for notes you own.

Your notes will outlive any app, any subscription, and any outage on exactly one condition: that more than one copy of them exists somewhere you control. Make the copies while everything is fine; the rule only feels trivial before you need it.

If this resonates, mnmnote.com keeps your notes as plain Markdown files on your own device — the kind you can copy, version, and back up anywhere, because they are yours.