7.4 How Properties Are Stored

WebDAV does not restrict the number of properties on a resource or in the repository, the maximum size for a property name or a property value, or the total amount of metadata that exists on a resource.

However, a few WebDAV server implementations may have such restrictions. For example, the default mod_dav configuration restricts the maximum size of a property to 8kb (although this can be increased by plugging in a different back end). This might make it infeasible for clients to store an image as a property (so usually images are stored as a resource body). Server designers should ensure that any property size limits are set appropriately high, because there isn't a good way in WebDAV to communicate the server's limits to the client. Instead, the server simply rejects the client's request with 507 Insufficient Storage, which might mean that the property is too big, the file is too big, the disk is full, or the user's quota is full.

Some WebDAV servers store property values in a database; others store them in special property value files in the file system, separately from the resource bodies. Some file systems are capable of storing streams of data alongside file body streams, in which case the properties can be stored in the data stream. Properties must be moved and copied with the resource entity no matter how they are stored. The choice of storage should not affect property values, character sets, or size.