How to Use Mountain Duck as a Caching Layer for NAS Storage
If you edit video off a NAS, you already know the pain. You scrub through a timeline and every frame has to travel across your network before it hits your screen. Previews stutter. Thumbnails load slowly. Opening the same project twice doesn't get any faster the second time, because your Mac treats every file read like it's never seen the file before.
The fix is a caching layer — an app that sits between Finder and your NAS, keeps a local copy of files as you open them, and serves them from your local drive on every subsequent read. That app is Mountain Duck.
Why Standard SMB Connections Are Slow
When you connect to a NAS the normal way — Finder's "Connect to Server" dialog, smb://192.168.x.x — macOS mounts the volume as a direct network share. Every single file operation goes back over the network to your storage box. Open a clip, that's a network read. Generate a thumbnail, network read. Scrub through the same clip you opened five minutes ago, network read again.
Your NAS might have a 1 Gbps or even 10 Gbps link, but that's shared bandwidth across every device on your network, and it's still orders of magnitude slower than a local SSD. For small files — documents, spreadsheets — you'll never notice. For video files measured in gigabytes, or a DaVinci Resolve project with hundreds of media references, it's the bottleneck that makes your entire editing experience feel sluggish.
The native SMB mount also gives you zero offline capability. Disconnect from the network and your files vanish from Finder entirely. If you're on a laptop moving between a studio and a home office, that means you can't even open your project on the train.
What Mountain Duck Actually Does
Mountain Duck is a macOS (and Windows) app that mounts remote storage as a virtual drive in Finder — similar to how Dropbox or Google Drive appear as local folders. The difference is it connects via standard protocols like SMB, SFTP, WebDAV, S3, and others, so it works with the NAS you already own.
The key feature is what they call smart sync. When you open a file, Mountain Duck downloads it to a local cache on your Mac's internal drive. The file now exists in two places: on your NAS and in your local cache. The next time anything reads that file — your NLE, a thumbnail generator, Finder's preview pane — it comes off the local SSD instead of crossing the network again.
Think of it like a script supervisor's binder sitting at the edit station. The first time you ask for a take, someone has to walk to the vault and bring it back. After that, it's right there on the desk. Mountain Duck automates the walk-to-the-vault part and keeps the binder organized.
The result is that your first open of a file is still network-speed. But every read after that is local-drive-speed. For video editing, where the same files get read hundreds of times during a session, the difference is dramatic.
Step-by-Step Setup
Mountain Duck is a paid app (one-time license or subscription). Download it from mountainduck.io. Once installed, it lives in your menu bar.
1. Create a New SMB Bookmark
Open Mountain Duck and create a new connection. Choose SMB as the protocol. This is the same protocol Finder uses when you connect to a network share — you're just routing it through Mountain Duck's caching engine instead.
2. Enter Your NAS Credentials
Use the same IP address, username, and password you normally use to connect via Finder. If your NAS is at 192.168.1.100 and you log in as leland, those go in exactly as-is.
3. Set the Path and Nickname
This is the one step that trips people up. In the path field, enter the name of the shared volume as it appears when you connect via Finder, with a forward slash at the front. If your volume is called Media, the path is /Media.
In the nickname field, enter the same name without the slash: Media. This is what the mount point will be called in Finder.
4. Set the Connection Mode to Smart Sync
This is the setting that enables caching. Mountain Duck offers several sync modes — smart sync is the one you want. It downloads files on demand as you access them and keeps them cached locally. Files you haven't opened remain as placeholder icons that download when you need them, similar to how iCloud Drive works.
5. Connect
Hit connect. You'll see a new volume appear in Finder's sidebar. It looks and behaves like a normal mounted drive, but every file you open gets cached to your local disk behind the scenes.
Cache Management and Offline Use
By default, Mountain Duck allocates a modest cache size. For video editing, you'll want to increase it.
Open Mountain Duck's preferences and look for the cache settings. You can set a maximum cache size in gigabytes. If you have a 1 TB internal SSD with 400 GB free, setting the cache to 200-300 GB gives you room to cache a significant chunk of your active project without starving your boot drive.
The larger your cache, the longer you can work offline. If you're cutting a project with 150 GB of source media and your cache is 200 GB, Mountain Duck will eventually have the entire project cached locally. At that point, you can disconnect from the network entirely and keep editing. Changes sync back when you reconnect.
Mountain Duck handles cache eviction automatically — oldest and least-recently-used files get purged first when the cache fills up. You don't have to manage it manually. If you want to force-cache specific files or folders before going offline, right-click them in Finder and select "Keep Offline" from the Mountain Duck context menu.
When This Matters Most
The caching layer pays for itself in a few specific scenarios:
Video editing off a NAS. This is the primary use case. Timeline scrubbing, waveform generation, thumbnail rendering, and conform operations all hammer the same files repeatedly. Caching means the first pass is slow and every subsequent pass is fast.
Large file previews. If you're browsing folders of RAW photos, ProRes clips, or PSDs on your NAS, Finder generates previews by reading each file. Over a standard network mount, scrolling through a folder of 4K ProRes files feels like loading a web page on dial-up. With caching, the previews stay local after the first load.
Laptop workflows between locations. If you move between a wired studio connection and a home office on Wi-Fi — or worse, a coffee shop with no access to your NAS at all — the offline cache means your active project files travel with you without any manual copying.
Remote NAS access. Mountain Duck supports connecting over the internet, not just local network. If you have a NAS at the office and need to pull files from home, the smart sync cache means you're not re-downloading the same 20 GB timeline every time you open your project.
How It Compares to Alternatives
Native SMB mount (Finder's "Connect to Server"). No caching. Every read goes over the network. No offline support. Free, but you pay for it in time.
Cyberduck. Same developer as Mountain Duck. Cyberduck is a file transfer client — think FTP app. It lets you browse and download files, but it doesn't mount a virtual drive or provide transparent caching. If you want to drag a file into your NLE, you have to download it first. Mountain Duck is the "mount it and forget it" version.
Synology Drive, QNAP Qsync, etc. These are NAS-vendor sync clients that work like Dropbox — they sync entire folders bidirectionally. The problem is they sync everything, not just what you need. If your NAS has 40 TB of archived projects and you only need one 200 GB project, these tools want to sync all 40 TB (or force you to cherry-pick folders). Mountain Duck's on-demand approach only downloads what you actually open.
Resilio Sync / Syncthing. Peer-to-peer sync tools. Powerful, but they require setup on both ends and sync entire folder trees. Better suited for backup and replication than for on-demand editing access.
JuiceFS-based solutions. If you're already running JuiceFS for distributed storage, the caching is baked into the filesystem layer itself. That's a more involved setup — a different weight class. Mountain Duck is the tool you install in five minutes and it just works with the NAS you already have.
Tying It Together
Mountain Duck solves a narrow problem extremely well: it makes editing off a NAS feel like editing off a local drive, without requiring you to manually copy files back and forth or overhaul your storage infrastructure. Download it, point it at your NAS, set smart sync, bump the cache size, and your next editing session will be noticeably faster from the second file read onward.
The setup takes less time than the coffee you'll drink while your first timeline caches. After that, it's invisible.