Snapshots & Versioning - Undo Mistakes with Btrfs

What a Snapshot Actually Is

A snapshot is a saved photo of your files exactly as they were at one moment in time. Think of it like a photograph of your desk taken at 3:00 PM. If you make a mess of the desk afterward, you can look at the photo and put everything back the way it was.

Your Synology can take these photos of a whole shared folder - all the files and folders inside it - in an instant. Later, if a file is deleted, changed, or damaged, you can open the snapshot from earlier and pull the good copy back out.

You Need a Btrfs Volume for This

Synology volumes come formatted in one of two file systems: Btrfs or ext4. Snapshots are a feature of Btrfs only. An ext4 volume simply cannot take snapshots - the ability is not there.

Btrfs (say it "butter-eff-ess") is the newer of the two. Besides snapshots, it can quietly check your files for damage. Most Synology models made in recent years use Btrfs by default, so there is a good chance you already have it.

• Open Storage Manager from the main menu.
• Look at your volume - it lists the file system as Btrfs or ext4.
• If it says Btrfs, you are ready for snapshots.
• If it says ext4, snapshots are not available on that volume.

The Snapshot Replication Package

The tool that manages snapshots on your Synology is a free add-on called Snapshot Replication. You install it once from Package Center, and it handles taking, scheduling, and restoring snapshots.

The name mentions "Replication" because the same package can also copy snapshots to a second Synology for extra safety. We will get to that later. For now, just know this is the home base for everything about snapshots.

• Open Package Center from the main menu.
• Search for "Snapshot Replication."
• Click Install and wait for it to finish.
• Open it - you will see your shared folders listed.

Taking Your First Snapshot

You can take a snapshot by hand any time you like - for example, right before you make a big change to a folder. It is a good habit and takes only a moment.

That is it. In a second or two, a new snapshot appears in the list with the date and time. Your files are untouched - you have simply saved a photo of this moment that you can return to later.

• Open Snapshot Replication.
• Go to the Snapshots section and pick the shared folder you want.
• Choose to take a snapshot now.
• Add a short note if it offers one, like "before cleanup," so you remember why.

Scheduling Snapshots Automatically

Taking snapshots by hand is fine now and then, but the real power comes from a schedule. Set it once and your Synology quietly takes snapshots on its own - forever - without you lifting a finger.

You set the schedule per shared folder inside Snapshot Replication. A folder you edit all day deserves hourly snapshots. A folder you barely touch is fine with daily or weekly. There is no single right answer - match it to how often the files change.

Retention: How Many to Keep

If your Synology took a snapshot every hour and never deleted any, the list would grow forever. A retention rule tells it how many to keep, so old ones are cleared out automatically as new ones arrive.

A common starting point is to keep the last 24 hourly snapshots and the last 30 daily ones. That gives you every hour of the past day and every day of the past month to fall back on. Adjust the numbers to fit your space and your needs.

• You set a number - for example, keep the last 24 hourly snapshots.
• When a new one is taken, the oldest beyond your limit is removed.
• You can layer rules - keep hourly for a day, daily for a month, and so on.

Restoring a Whole Folder

Suppose a folder got scrambled - files deleted, moved, or changed all at once. You can roll the entire folder back to how it looked in an earlier snapshot, all in one go.

Restoring a whole folder replaces the current contents with the older version. That is exactly what you want when the whole folder is a mess, but it does mean any good changes made after that snapshot are set aside too. When in doubt, restore a single file instead - that is next.

• Open Snapshot Replication and go to the Snapshots list for that folder.
• Find a snapshot from before things went wrong - check the date and time.
• Choose to restore that snapshot.
• Confirm, and the folder returns to that earlier state.

Restoring Just One File

Most of the time you only need one file back - a document you saved over, or a photo you deleted. You do not have to roll back the whole folder. You can reach into a snapshot and grab just that one item.

If snapshots are set to be visible, you can right-click a folder on the Synology drive in Windows and choose Restore previous versions (also called Previous Versions). Windows shows the older copies saved in the snapshots, and you can restore or copy the one you want. On a Mac, this Windows shortcut is not available, so use File Station instead.

• Open File Station and go to the folder.
• Look for a way to browse previous versions of the folder from snapshots.
• Find the older copy of the file and copy it back out.

How Much Space Snapshots Use

A brand-new snapshot uses almost no space, because it only records what was there. Space is used gradually, as your files change over time and the snapshot has to remember the older versions.

This is why retention rules matter. As old snapshots are cleared out, the space they held is freed up. A folder of files that rarely change will use very little snapshot space even over months. A folder of large files that change constantly will use more.

• Take a snapshot: almost no space used at first.
• Change or delete files afterward: the snapshot keeps the old versions, using space.
• The more your files change, the more your snapshots grow.

Locked Snapshots vs Ransomware

Ransomware is nasty software that scrambles your files and demands money to unscramble them. A locked snapshot is one of your best defenses, because it is frozen and cannot be changed or deleted - even by the ransomware.

A normal snapshot could, in theory, be deleted by an attacker who gets into your system. A locked - also called immutable - snapshot is protected for a set period. During that time, nobody can remove it, so you always have a clean copy from before the attack to restore from.

• In the snapshot settings, look for the option to lock snapshots.
• Set how long they stay locked - for example, a week.
• During that window, that snapshot cannot be deleted by anyone.

The Big Rule: A Snapshot Is NOT a Backup

This is the most important page in the guide. Snapshots are wonderful for undoing mistakes, but they are not a backup. They live on the very same Synology as your files - the same drives, the same box, in the same room.

If a drive fails, the snapshots on it are gone too. If the whole NAS dies, is stolen, or a pipe bursts or a fire breaks out, your files AND your snapshots vanish together. A snapshot protects against mistakes and changes - not against losing the machine itself.

Replicating Snapshots to a Second NAS

The same package that makes snapshots can also copy them to a second Synology - that is the "Replication" in the name. Now your snapshots live in two places, so losing one NAS does not lose everything.

This turns snapshots from an undo button into something much closer to a real safety net, because your data now exists in more than one place. Many small businesses keep a second Synology at another location just for this.

• The second NAS can sit in another room, another building, or another site.
• If the first NAS fails, the second one still holds your snapshots.
• You can set replication on a schedule, so it stays current on its own.

Snapshots vs Hyper Backup

Snapshots and Hyper Backup are both about safety, but they do different jobs. You want both. Here is when each one shines.

Think of snapshots as your quick everyday undo, and Hyper Backup as your disaster insurance. Snapshots get you a deleted file back in seconds. Hyper Backup gets your whole life back if the NAS itself is lost. Neither replaces the other.

Letting People Recover Their Own Files

One of the nicest things about snapshots is that people can often get their own files back without calling anyone. If you run a small office, this saves everyone time and worry.

No admin password, no phone call, no waiting. Because snapshots are read-only, there is no risk of them harming anything else while they browse older versions. They can only look and copy back out.

• You turn on snapshot visibility for the shared folder.
• A person right-clicks the folder in Windows and picks Restore previous versions.
• They pick the older copy and restore it themselves.

Testing a Restore Before You Need It

A safety net you have never tested is just a hope. Take ten minutes now, while nothing is wrong, to prove to yourself that restoring works. Then you will trust it when it counts.

That is the whole drill. Once you have watched a file come back with your own eyes, snapshots stop being a mystery. You will know exactly what to do on the day a real file goes missing.

• Create a spare file called "test.txt" in a snapshotted folder.
• Wait for the next snapshot, or take one by hand.
• Delete the spare file.
• Restore it from the snapshot using File Station or Windows Previous Versions.
• Confirm the file came back exactly as it was.

Setting It and Forgetting It

Once your schedule and retention are in place, snapshots run on their own. You do not have to babysit them. But a light touch now and then keeps everything healthy.

That is all the upkeep there is. The beauty of snapshots is that the hard part - remembering to protect your files - is handled for you automatically, every hour or every day, without a single reminder on your calendar.

• Once a month, glance at Storage Manager to see snapshot space.
• Once in a while, do a quick test restore to keep your confidence up.
• If you add important new folders, set up snapshots for them too.

Common Mistakes to Avoid

Every one of these is easy to sidestep once you know about it. A quick read now saves a headache later.

• Thinking snapshots are a backup. They are not - they live on the same NAS. Also run Hyper Backup.
• Never testing a restore. An untested safety net is just a guess. Practice once with a spare file.
• Keeping too few snapshots. If you only keep a couple, you cannot reach back far enough. Set sensible retention.
• Forgetting to turn on visibility. Without it, people cannot browse previous versions themselves.
• Not snapshotting new folders. A folder you add later has no snapshots unless you set them up.

A Simple Snapshot Plan

Here is a calm, sensible plan you can put in place today. Adjust the numbers to fit your files and your space - but this is a solid starting point for most homes and small offices.

• Confirm your volume is Btrfs, and install Snapshot Replication.
• On your most important folder, take a snapshot every hour during the day.
• On photos and documents, take one snapshot a day.
• Keep the last 24 hourly and the last 30 daily snapshots.
• Turn on snapshot visibility so people can self-recover files.
• Turn on locked snapshots for extra ransomware protection.

What's in the 27-page PDF

• What a snapshot really is, and why it feels like magic
• Why you need a Btrfs volume, and how to check yours
• Turning on schedules and how many copies to keep
• Getting a whole folder - or a single file - back
• Locked snapshots that help against ransomware
• The one big rule: a snapshot is NOT a backup

Why I wrote this

I write these as printable handouts because a guide you can keep in a drawer beats a web page you have to find again. No jargon, no judgment, no rushing. If you'd rather have someone sit beside you and go through it together, that's a flat $99 first visit with the 30-day follow-up included — serving Portage County from Atwater, Ohio. — Bill