LiteSpeed Web Server can save network bandwidth by sending gzip-or-brotli-compressed responses for both static and
dynamically generated content. The level of compression and situations
under which compression occurs can be configured in the gzip compression section
of the WebAdmin console (Configuration > Server > Tuning). You
first must make sure Enable Compression is set to
Yes, then set
compression rules for static and dynamic content separately.
Note: Enable Compression and Enable GZIP Dynamic Compression are enabled by default at installation.
When a request for a static file comes in (and compression is enabled),
the web server first looks for a corresponding gzip-compressed version
in the static gzip cache directory. The compressed file found in this
directory will be used if it is newer and smaller than the original one.
If the compressed file does not exist or is out of date, the web server
can create/update the gzip-compressed file automatically if Auto
Update Static is set to
Because compression is a server-intensive process, the web server will only compress files with a potentially high compression rate based on the following rules:
- The MIME type is set in Compressible Types (for example:
- The file size is between the Min Static File Size and the Max Static File Size.
Be careful not to set the Max Static File Size too large. The server cannot process other requests while it is compressing a static file. Compressing very large files will thus result in delayed service.
The web server can perform run-time compression for
dynamically generated content as well. To turn on compression for
dynamic content, both Enable Compression and Enable Dynamic
Compression must be set to
Both static and dynamic file compression can be tuned to your server and network capabilities using Compression Level (Static File) and Compression Level (Dynamic Content). Better compression (a higher number) will save bandwidth, but will use more memory and CPU cycles. Your specific CPU and bandwidth saving needs determine the ideal configuration for your system.
After setting up compression rules as shown above, you can verify that
it is working by opening the file URL in your browser in the format:
Server_IP:Port_num/path_to_file. Enter your browser's
Development/Inspector Tool and navigate to Network > Headers. You
Content-Encoding: gzip as shown below:
If the page is returned with no compression, (i.e. no
header), verify that you are using a pre-defined MIME type. Note that
text/xml is not a pre-defined MIME type, so
text/* won't match it.
Adding a New Pre-defined MIME Type¶
Navigate to Web Admin Console > Server > General > General Settings
MIME Settings** and open
$SERVER_ROOT/conf/mime.properties. Scan the file for your desired MIME type.
If your MIME type is not there, you can add it in one of two ways:
Navigate to Web Admin Console > Server > Tuning > GZIP Compression > Edit > Append Compressible Types and append the MIME type (e.g.
text/xml) to the list manually. Save and then Graceful Restart.
Navigate to Web Admin Console > Server > General > General Settings > MIME Settings, click on
$SERVER_ROOT/conf/mime.propertiesand add the MIME type entry under Suffixes and MIME type (e.g.
text/xml). Save and then Graceful restart.
text/xml is just an example. You can add any MIME type you wish:
Disabling at the Virtual Host Level¶
Gzip compression can normally be enabled/disabled from the server
level. However, sometimes you
may have to control the gzip compression for a particular virtual host
.htaccess without affecting the global settings. There are two
ways to turn off gzip dynamically:
- a rewrite rule
The latter is a better choice, as it won't be affected by other rewrite rules.
Use Rewrite Rule
Place the following in
RewriteRule . - [E=no-gzip:1]
Be aware that other rewrite rules may affect it.
Place the following in
SetEnv no-gzip 1