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How do you back up a folder to a NAS on a Mac?

By Kayabyte · Last updated 13 November 2026

Short answer: Mount the NAS in Finder (Go, Connect to Server, then smb://name-or-address), then copy the folder there, run rsync against the mounted share, or let an app do it on a schedule. Time Machine can also use a network share as its disk, but it backs up the whole Mac. Pairfold can mirror a folder to a share you have mounted in Finder, with a preview and an archive of replaced files. We tested its copy engine against an SMB share in a virtual machine; we did not test choosing a share folder through the app’s file panel on a real NAS, so try it with a small folder first.

Method 1: Connect to Server and copy

In Finder choose Go, Connect to Server, type the NAS address, for example smb://nas.local, and sign in. The share appears under Locations and in /Volumes. Drag your folder onto it. That works for a first copy. It does not repeat, and Finder will ask Replace or Stop if the folder exists.

Method 2: rsync to the mounted share

rsync -avn ~/Photos/ /Volumes/media/Photos/ shows what would be copied (-n). Without -n it copies. Network shares are slower than drives and can drop. If the share is not mounted, /Volumes/media may not exist and rsync can create a plain folder on your Mac’s disk, so test for the folder in a script before you run rsync. Some NAS file systems store times coarsely: if every run copies everything again, try --modify-window=2.

Method 3: Time Machine

Time Machine can back up to a network share if the NAS supports it. It protects the whole Mac with history. It is a good answer if that is what you want, and a bad one if you only want one folder in readable form on the NAS. See Time Machine vs folder sync.

With Pairfold

Mount the share in Finder first, then choose a folder on it when you make the pair. Mirror mode makes the share’s folder match yours and never changes yours. If the share is not connected when a run starts, Pairfold stops with “disk not connected” and writes nothing, and with Run when a disk or share is connected turned on it runs once the share mounts again. If the connection drops mid-copy, the file being copied is not put in place and the old one stays.

What we tested: the copy engine against an SMB share in a virtual machine (copy, archive, replace, and a share dropped in the middle of a 300 MB file). What we did not test: choosing a folder on a share through the open panel in the sandboxed app, on a real NAS box. Pairfold does not log in to a NAS itself; it only uses what Finder has mounted.

Steps with Pairfold

  1. In Finder, connect to the NAS with Go, Connect to Server and open the share.
  2. In Pairfold click New Pair, choose your folder, then a folder on the share.
  3. Choose Mirror, click Check and Preview, read the list and click Sync.
  4. In the pair’s settings choose a schedule or Run when a disk or share is connected.

Get Pairfold: see the app page for where to get it

Questions

Does Pairfold connect to my NAS by itself? No. Mount the share in Finder and choose a folder on it.

Can it use FTP or SFTP? No. Pairfold works with folders and mounted shares only.

Is a NAS copy a backup? It is a second copy. If you delete or damage files in the source and mirror again, the copy follows. Pairfold moves replaced and removed files to an archive on the share, which helps, but keep a second backup of anything irreplaceable.

Why is it slow? Network speed. A first copy of a large photo collection can take hours; later runs only copy what changed.

Apple, Mac, macOS, Finder, Time Machine, and iCloud are trademarks of Apple Inc. Pairfold is made by Kayabyte and is not affiliated with or endorsed by Apple.