Sync used to be all-or-nothing: connect a laptop to a big Team Folder and watch its small SSD fill up. On-demand sync changes the deal — every file appears, almost none are stored, and each one downloads the moment you open it. Here is how to use it without getting caught out.
Modern laptops ship with fast but small SSDs, while office Team Folders grow without mercy. On-demand sync in Synology Drive Client is built for exactly this clash: the folder structure and file names live on the laptop, but the file contents stay on the NAS until needed. It is a genuinely useful feature — with two limits you must understand before a train journey teaches them to you.
With on-demand sync enabled for a sync task, Drive Client creates placeholder files — they have the right names, sizes and icons, but take almost no space. Double-click one and the real file downloads on the spot, then opens normally; from then on it behaves like a local file and syncs changes back. Files you stop using can be released again with a right-click (free up space), turning them back into placeholders while the copy on the NAS stays untouched. On Windows this works hand-in-hand with the system's Files On-Demand behaviour, and the client shows the status of each file with small overlay icons — cloud for placeholder, tick for downloaded.
The feature has a second control that matters as much as the first: pinning. A pinned file or folder is always kept fully on the laptop, downloaded and current, whether or not you have opened it lately. Pin these:
Pinning is a five-second right-click. Doing it the evening before a trip is the entire secret to on-demand sync never embarrassing you.
A placeholder is a promise, not a file. On a plane, in a basement office, at a client site with broken guest Wi-Fi — an unpinned, never-opened file simply cannot be opened, because its contents are 40 km away on your NAS. This is not a flaw to complain about; it is the physics of the feature. The failure mode is always human: somebody assumed 'I can see it in the folder' meant 'I have it'. Teach the team the icon language — cloud means not really here — and the problem mostly disappears.
A few workloads sit badly with placeholders, honestly stated:
For a media-heavy or project-file workflow, a plain full sync of that one folder, or working on the office LAN, is still the better tool. On-demand sync is perfect for documents — which is most office work.
When the SSD fills anyway, release space only through Drive's own option — right-click a downloaded file or folder and choose the free up space / release action in the Synology Drive menu. Never 'clean up' by deleting placeholder files by hand: deleting a synced file is an instruction to delete it on the NAS for everyone, not a local tidy-up. And remember what on-demand sync does not do: it saves space on the laptop only. The NAS still stores everything, in full, as it should.
Watch the full Synology Drive setup video to see sync tasks created and the client options explained on a real PC.
▶️ Watch Full VideoNo — it only changes what is stored on the computer. The NAS always holds the complete, real files. That is exactly what you want: the laptop is the cache, the NAS is the truth.
Yes — the choice is made per sync task, so a laptop can keep the current project fully synced while browsing the big archive folder on demand. Set it task by task according to how each folder is used.
You can edit files that are fully downloaded or pinned — changes are saved locally and sync up automatically when the connection returns. Just remember that placeholders cannot be opened offline at all, which is why pinning before travel matters.