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Use in Finder

Open Finder. You'll see OneLake in the sidebar under Locations. Inside:

~/OneLake/
├── work/
│   └── Sales Analytics/
│       └── BronzeLake.lakehouse/
│           ├── Files/
│           │   └── raw/
│           │       └── 2026-Q2.csv
│           └── Tables/
└── client-a/
    └── ...

What just works

  • Drag-and-drop to upload.
  • Double-click to open. Files are streamed from OneLake on demand and cached locally, so a second open is instant.
  • Save in any app to write back to OneLake.
  • Spotlight indexes file names (not contents — that would download the entire lake).
  • Quick Look previews CSVs, images, PDFs without downloading.
  • Right-click → "Always Keep on this Mac" for offline access.
  • Right-click → "Free up space" to drop the local copy and keep the placeholder.

What is special

  • Online-only placeholders by default. Files show a cloud icon until you open them. This keeps your disk usage low even if a lakehouse is huge.
  • Per-account folders. Different accounts and different tenants live next to each other; you never need to "switch account".
  • Adaptive sync. Folders you're actively browsing refresh every 30 seconds; folders you visited recently every 5 minutes; the rest on-demand. The daemon does this in the background.

What you can't do from Finder

A few things are managed entirely by Microsoft Fabric and aren't exposed through the file-system layer:

  • Create or rename a workspace or lakehouse — go to the Fabric portal.
  • Manage permissions — go to the Fabric portal.
  • Change the schema of a Delta table inside Tables/ — OneLake rejects writes that would corrupt the Delta log; safe but you'll see "operation not permitted" if you try.

Files OFEM doesn't upload

macOS scatters small metadata files everywhere (.DS_Store, ._foo, .Spotlight-V100, .Trashes, .fseventsd). OFEM silently filters them on upload so they never reach your lake. You won't see them in OneLake even though they exist locally.

Multiple Macs

The same OneLake account can be added on multiple Macs. Each Mac has its own local cache and its own LaunchAgent; OneLake is the source of truth, so changes made on one Mac become visible on the others on the next adaptive-poll cycle (typically within 30 seconds for an actively-browsed folder).

Performance expectations

  • Listing a folder with up to a few hundred items: instant from cache, well under a second from OneLake.
  • Opening a file: limited by your network. A 100 MB CSV typically streams in 1–3 seconds on a fibre connection.
  • Uploading: chunked at 4 MiB. A 1 GiB file uploads in roughly minute-and-some on a 100 Mbit upload.
  • Background poller: refreshes touched folders every 5 minutes; load is negligible.

When the network is gone

  • Files you've opened recently are in the local cache and remain readable.
  • New reads and uploads queue and retry when the network returns.
  • The menu-bar status icon switches to "offline".