Back up SD cards to a Synology NAS from a Mac

Sync Shutter guide · Mac · needs Sync Shutter Pro

Insert a card, and a copy lands on the NAS before you have opened Lightroom. Sync Shutter reaches a NAS two ways: over SFTP, which Synology DSM has built in, or over the S3 API, which needs an S3-compatible server running on the NAS. SFTP is the simpler route on a Synology. Both are part of Sync Shutter Pro, a one-time $0.99 purchase that unlocks Mac, iPhone, and iPad.

What you need

• Sync Shutter on the Mac, with Pro unlocked (Settings → Pro).
• A NAS the Mac can reach on the network, by IP address or a name such as nas.local.
• A NAS user with write access to the folder that will hold the backups.

Route A: SFTP (recommended on a Synology)

On the NAS

1. Turn on SFTP. In DSM it lives under Control Panel → File Services, on the FTP tab. Check DSM's help for the exact screen on your version.
2. Create or choose a shared folder for card backups, for example Backups, and give your user read and write permission on it.

In Sync Shutter

1. Open Settings and find SFTP / NAS (SSH). Click Add.
2. Name: anything, for example Home NAS.
3. Host: the NAS address, for example 192.168.1.100 or nas.local.
4. Port: 22 unless you changed it in DSM.
5. Remote path: the absolute path on the NAS. On most Synology units shared folders live under /volume1, so a shared folder called Backups is /volume1/Backups. Sync Shutter creates any missing folders below that path, so /volume1/Backups/SDCards works even before SDCards exists.
6. Username and Password for the NAS user. Sync Shutter supports password sign-in only; SSH key files are not supported yet. The password is stored in the macOS Keychain.
7. Click Test Connection, then Save.

The first connection pins the NAS's SSH host key (trust on first use). If that key ever changes, for example after DSM is reinstalled, backups to that destination stop with a message explaining why, and you remove and re-add the destination to trust the new key. A changed key with no reinstall behind it is a reason to look at your network before trusting it.

Route B: S3-compatible

DSM does not include an S3 server, so this route needs one running on the NAS, for example MinIO in Container Manager. The same destination type also works with MinIO on any machine, and with Backblaze B2 or Wasabi. Unlike SFTP, S3 destinations are also available in Sync Shutter on iPhone and iPad.

On the S3 server

1. Create a bucket, for example photos.
2. Create an access key and secret key with permission to list the bucket and put objects into it.

In Sync Shutter

1. Open Settings and find S3 Compatible (NAS). Click Add.
2. Name: for example Home NAS.
3. Endpoint: the server URL with its port, for example http://192.168.1.100:9000. Sync Shutter uses path-style addressing for every endpoint that is not Amazon's, which is what MinIO expects.
4. Bucket: the bucket you created.
5. Region: whatever the server was configured with. The region is part of the request signature, so a mismatch shows up as a signing error even though the network is fine. us-east-1 is MinIO's default.
6. Prefix: the folder inside the bucket, default SDBackup.
7. Storage Class: leave it on Standard. The other tiers exist for Amazon S3; a NAS, MinIO, B2, or Wasabi can reject an upload that asks for one.
8. Access Key ID and Secret Key. Both are stored in the Keychain.
9. Click Test Connection, then Save.

What lands on the NAS

Files keep their card layout below the path or prefix you chose, so a Sony card produces SDCards/100MSDCF/DSC00123.ARW. With Organize files by date on in Settings, a date folder is inserted first, in one of three layouts: 2026/2026-09-02, 2026/2026-09, or 2026-09-02. The date comes from the photo's EXIF data.

Backups are incremental: a card you insert again only sends the files that are new since last time. Verify file integrity after backup checksums each copy. If the NAS is unreachable when the card goes in, the local copy still runs and the NAS upload is queued and retried when the network comes back.

With more than one camera, Per-Card Rules (also Pro) send each card to its own set of destinations, so a second body's cards can go to the NAS while the first goes to a cloud service, or the other way round.

If something fails

• Connection failed: check the host, the port, and that SFTP or the S3 server is actually running. Try the same address from a terminal or another SFTP client.
• Upload failed on an S3 destination with a tier other than Standard: set the storage class back to Standard.
• Host key changed on SFTP: see above. Remove and re-add the destination only if you know the NAS was reinstalled.
• A backup that reached the Mac but not the NAS says Backup Incomplete and names the NAS destination, so you know which copy to check.

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