Microsoft is raising the number of items OneDrive will keep in sync on a Mac from 300,000 to 1,000,000, matching the limit already available on Windows.
The higher ceiling entered preview in the Insiders ring this month. General availability is targeted for June 2027.
It will not apply everywhere. Only devices that meet Microsoft's hardware and configuration requirements qualify; the rest keep the existing 300,000-item limit.
The company's stated reason is scale. "This increase is intended to help organizations with large OneDrive and SharePoint libraries," Microsoft said.
It is also candid that the experience at the new ceiling remains a work in progress. "We are actively working to improve performance and reliability for these scenarios," it said.
Two caveats are flagged. Sync performance may suffer where there are large numbers of read-only files, or where accounts are under legal hold. Automatic link expiration controls, which any organisation needing time-limited access would want first, are described as still coming.
The change arrives alongside other OneDrive work. Copilot in OneDrive can analyse across several files, organise folders and save a repeated workflow as a personal skill in a Markdown file, and there is a Prompt Gallery. Hero Links give one link per file and folder by default, so permissions can change without the address changing. A OneDrive Sync command-line tool for administrators, which inspects accounts, configuration, policies and sync status, is in private preview.
The announcement treats the old limit as the obstacle, which invites the question of what the limit was for. A sync ceiling is not a storage ceiling. It is a cap on the number of separate objects a machine has undertaken to keep identical to a copy held somewhere else.
Raised to a million, that undertaking becomes the largest single promise a laptop makes. Each of the million items is a commitment that two versions of something agree. The commitment is continuous, it is renewed on every change, and it is made by a device that also has to open a browser.
The practical effect of the change is therefore an increase of 700,000 in the number of things that can be out of date on one Mac. Microsoft has not disputed this. It has said that it is actively working to improve performance and reliability for these scenarios.
Our analysts note that the previous limit was never a defect. At 300,000 items it was the only component of the architecture that limited exposure, and it has now been raised by a factor of 3.3 with general availability still eight months away. The Department of Unnecessary Research has a single question for the Insiders ring, which is whether anybody has yet reached a million items, and whether they noticed.