Skip to content

slowfs: NGINX SlowFS Cache Module


You can install this module in any RHEL-based distribution, including, but not limited to:

  • RedHat Enterprise Linux 7, 8, 9
  • CentOS 7, 8, 9
  • AlmaLinux 8, 9
  • Rocky Linux 8, 9
  • Amazon Linux 2 and Amazon Linux 2023
yum -y install
yum -y install nginx-module-slowfs

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

load_module modules/;

This document describes nginx-module-slowfs v1.11 released on Aug 23 2020.

ngx_slowfs_cache is nginx module which allows caching of static files (served using root directive). This enables one to create fast caches for files stored on slow filesystems, for example:

  • storage: network disks, cache: local disks,
  • storage: 7,2K SATA drives, cache: 15K SAS drives in RAID0.

WARNING! There is no point in using this module when cache is placed on the same speed disk(s) as origin.


ngx_slowfs_cache was fully funded by


This module is production-ready and it's compatible with following nginx releases:

  • 0.7.x (tested with 0.7.60 to 0.7.69),
  • 0.8.x (tested with 0.8.0 to 0.8.55),
  • 0.9.x (tested with 0.9.0 to 0.9.7),
  • 1.0.x (tested with 1.0.0 to 1.0.15),
  • 1.1.x (tested with 1.1.0 to 1.1.19),
  • 1.2.x (tested with 1.2.0 to 1.2.7),
  • 1.3.x (tested with 1.3.0 to 1.3.14).

Configuration notes

slowfs_cache_path and slowfs_temp_path values should point to the same filesystem, otherwise files will be copied twice.

ngx_slowfs_cache currently doesn't work when AIO is enabled.

Configuration directives


  • syntax: slowfs_cache zone_name
  • default: none
  • context: http, server, location

Sets area used for caching (previously defined using slowfs_cache_path).


  • syntax: slowfs_cache_key key
  • default: none
  • context: http, server, location

Sets key for caching.


  • syntax: slowfs_cache_purge zone_name key
  • default: none
  • context: location

Sets area and key used for purging selected pages from cache.


  • syntax: slowfs_cache_path path [levels] keys_zone=zone_name:zone_size [inactive] [max_size]
  • default: none
  • context: http

Sets cache area and its structure.


  • syntax: slowfs_temp_path path [level1] [level2] [level3]
  • default: /tmp 1 2
  • context: http

Sets temporary area where files are stored before they are moved to cache area.


  • syntax: slowfs_cache_min_uses number
  • default: 1
  • context: http, server, location

Sets number of uses after which file is copied to cache.


  • syntax: slowfs_cache_valid [reply_code] time
  • default: none
  • context: http, server, location

Sets time for which file will be served from cache.


  • syntax: slowfs_big_file_size size
  • default: 128k
  • context: http, server, location

Sets minimum file size for big files. Worker processes fork() child process before they start copying big files to avoid any service disruption.

Configuration variables


Represents availability of cached file.

Possible values are: MISS, HIT and EXPIRED.

Sample configuration

http {
    slowfs_cache_path  /tmp/cache levels=1:2 keys_zone=fastcache:10m;
    slowfs_temp_path   /tmp/temp 1 2;

    server {
        location / {
            root                /var/www;
            slowfs_cache        fastcache;
            slowfs_cache_key    $uri;
            slowfs_cache_valid  1d;

        location ~ /purge(/.*) {
            allow     ;
            deny                all;
            slowfs_cache_purge  fastcache $1;


ngx_slowfs_cache comes with complete test suite based on Test::Nginx.

You can test it by running:

$ prove

See also


You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-slowfs.