Offline Files is a feature of Sync Center that makes network files available to a user, even if the network connection to the server is unavailable.
Users can use offline files (if enabled) to make their network files always available offline to keep a copy of the files stored on the network on your computer. This allows users to work with them even when they are not connected to the network or a server is unavailable. The next time the user connects to the network or the server is available, their offline files on your computer will automatically sync to the network files on the server to update.
Offline files for all users on the computer are stored in the protected C:\Windows\CSC folder by default.
The size and number of your offline files determine how much hard disk space your offline files use. This includes the space used by automatically cached files and files that are specifically made always available offline. Files can be automatically cached if the user accesses a file on an automatic caching network share.
Files that were cached automatically are removed on a least-recently used basis if the maximum cache size is reached.
Files that were cached manually (always available offline) are never removed from the local cache. When the total local cache size limit is reached and all files that were cached automatically have already been removed, you can not make files available offline until you specify a new limit or delete files from the local cache by using the Offline Files control panel applet.
By default, Windows limits the space that offline files occupy to 25 percent of the total space on the drive where the Offline Files cache (ex: “C:\Windows\CSC”) is located. The limit for automatically cached files (temporary files) is 100 percent of the total disk space limit.
If you like, you can specify the disk space limit (in megabytes) for offline files and also specify how much of that disk space can be used by temporary files (automatically cached files) for all users on the computer.
This tutorial will show you how to view and change the maximum Offline Files disk usage limits for all users in Windows 7, Windows 8, and Windows 10.