Context: http, server, location

If this directive is enabled, Nginx will use the sendfile kernel call to handle file transmission. If disabled, Nginx will handle the file transfer by itself. Depending on the physical location of the file being transmitted (such as NFS), this option may affect the server performance.

On Linux, using sendfile automatically disables asynchronous IO. If using FreeBSD, it is possible to combine the use of aio and sendfile; more on this in Chapter 8, From Apache to Nginx.

Syntax: on or off

Default value: off