When Nginx acts as a reverse proxy, it often struggles with large downloads because it tries to buffer the response from the upstream server. Nginx Serving static large file - Stack Overflow
: While sendfile is excellent, it can be blocking on some systems. Enabling asynchronous I/O (AIO) with a thread pool allows Nginx to handle disk reads in the background without blocking the main worker processes.
: This is the most critical setting. It allows Nginx to use the sendfile() system call, which transfers data directly between the file descriptor and the network socket at the kernel level. This avoids copying data into the user-space buffer, drastically reducing CPU usage. nginx download big files
: This overrides Nagle's algorithm to ensure small packets are sent immediately. For large downloads, it helps maintain a consistent flow.
: Used exclusively with sendfile , this directive tells Nginx to send the HTTP response headers and the beginning of the file in one packet, improving network efficiency. When Nginx acts as a reverse proxy, it
: For exceptionally large files (e.g., ISOs or video files), you can use directio . This bypasses the OS page cache for files larger than the specified size, preventing a single massive download from "flushing" smaller, frequently accessed files out of the system RAM. Handling Proxy and Buffering Issues
For serving large files stored locally on the server, Nginx provides several kernel-level optimizations to reduce CPU overhead and disk I/O. : This is the most critical setting
To optimize Nginx for downloading large files, you must balance kernel-level performance, memory management, and network stability. By default, Nginx is tuned for small, high-concurrency requests, which can lead to timeouts or disk thrashing when handling multi-gigabyte downloads. Core Directives for Static Large Files