OpenLiteSpeed Web Server Users' Manual

Version 1.4 Rev. 1

Server General

General settings for the whole server. When path information is required in a setting, it can be either absolute or relative to $SERVER_ROOT. $SERVER_ROOT is the location where LiteSpeed web server has been installed (your_home_dir/lsws or /opt/lsws, for example). The server executable is under $SERVER_ROOT/bin.

Table of Contents

Server Process

Server Name | Number of Workers | Running As | Priority | Max I/O Buffer Size | Swapping Directory | Auto Fix 503 Error | Enable HTTP/2 Over Cleartext TCP | Graceful Restart Timeout | 

General Settings

MIME Settings | Suffixes | MIME Type | Disable Initial Log Rotation | Server Signature | Enable IP Geolocation | Use Client IP in Header | Administrator Email | 

Index Files

Index Files | Auto Index | Auto Index URI | 

Expire Settings

Enable Expires | Expires Default | Expires By Type | 

IP to Geolocation DB

DB File Path | DB Cache Type | 

Server Log

File Name | Log Level | Debug Level | Rolling Size | Enable stderr Log | 

Access Log

File Name | Piped Logger | Log Format | Log Headers | Rolling Size | Keep Days | Compress Archive | 

Server NameGo to top
Description: A unique name for this server. You can use $HOSTNAME as value.
Number of WorkersGo to top
Description: Specifies the number of httpd workers.
Syntax: Integer value between 1 and 16.
Tips: [Performance] Set an appropriate number to suit your needs. Adding more workers may not necessarily mean better performance.
Running AsGo to top
Description: Specifies the user/group that the server process runs as. This is set using the parameters "--with-user" and "--with-group" when running the configure command before installation. To reset these values, you must rerun the configure command and reinstall.
Apply: Reinstall required.
Tips: [Security] Server should not run as a privileged user such as "root". It is critical that the server is configured to run with a un-privileged user/group combination that does not have login/shell access. A user/group of nobody is generally a good choice.
PriorityGo to top
Description: Specifies priority of the server processes. Value ranges from -20 to 20. A lower number means higher priority.
Syntax: Integer number
Tips: [Performance] Usually, higher priority leads to slightly higher web performance on a busy server. Do not set priority higher than that of database processes.
See Also: External App Priority, CGI Priority
Max I/O Buffer SizeGo to top
Description: Specifies the maximum buffer size that is used to store a request body and its dynamically generated response. When this limit is reached, the server will start to create temporary swapping files under Swapping Directory.
Syntax: Integer number
Tips: [Performance] Set the buffer size large enough to accommodate all concurrent requests/replies to avoid memory to disk swapping. If there is frequent I/O activity to the swap directoy, by default /tmp/lshttpd/swap/, this buffer size is too low and LiteSpeed is swapping to disk.
See Also: Swapping Directory
Swapping DirectoryGo to top
Description: Specifies the directory where the swapping files should be placed. When the server started in chroot mode, it is relative to the new root directory, otherwise it is relative to the real root.

LiteSpeed web server uses its own virtual memory to reduce the system memory usage. Virtual memory and disk swapping is used to store big request bodies and dynamically generated responses. The swapping directory should be placed on a disk with enough space.
Syntax: Absolute path.
Tips: [Performance] Place the swapping directory on a separate disk or increase Max I/O Buffer Size to eliminate swapping.
See Also: Max I/O Buffer Size
Auto Fix 503 ErrorGo to top
Description: Specifies whether to try to fix the "503 Service Unavailable" error by restarting the web server gracefully. A "503" error is usually caused by malfunctioning external applications and a web server restart can often fix the error temporarily. If enabled, the server will restart automatically whenever there are more than 30 "503" errors within a 30 seconds span. This feature is enabled by default.
Syntax: Select from radio box
Enable HTTP/2 Over Cleartext TCPGo to top
Description: Specifies whether to enable HTTP/2 over non-encrypted TCP connections. Default is disabled.
Syntax: Select from radio box
Graceful Restart TimeoutGo to top
Description: During a graceful restart, even after the new server instance is up, the old instance will continue to handle existing requests. This timeout defines how long the previous instance shall wait before exit. Default value is 300 seconds. -1 means wait forever. 0 means no wait and abort immediately.
Syntax: int
MIME SettingsGo to top
Description: Specifies the file that contains the MIME settings for this server. It is always relative to the real root when an absolute path is given in chroot mode. Click on the file name to view/edit the detailed MIME entries.
Syntax: File name which can be an absolute path or relative to $SERVER_ROOT.
Tips: Click the file name to edit the MIME settings.
SuffixesGo to top
Description: You can list multiple suffixes for the same MIME type, using comma to separate.
MIME TypeGo to top
Description: A MIME type consists of a type and subtype in the format of "type/subtype".
Disable Initial Log RotationGo to top
Description: Specifies whether to disable rotation of server error log file at startup. Initial log rotation is enabled by default for standard installations.
Syntax: Select from radio box
Server SignatureGo to top
Description: Specifies whether to show the server signature and version number in the response header Server value. There are three options: When set to Hide Version, only LiteSpeed is shown. When set to Show Version, the LiteSpeed and the version number are shown. When set to Hide Full Header, the whole Server header will not be shown in the response header.
Syntax: Select from radio box
Tips: [Security] Set to Hide Version if you do not wish to expose the server version number.
Enable IP GeolocationGo to top
Description: Specifies whether to enable IP geolocation lookup. It can be set at server-, virtual host-, or context-level.
Syntax: Select from radio box
See Also: Use Client IP in Header, DB File Path, DB Cache Type
Use Client IP in HeaderGo to top
Description: Specifies whether to use the IP address listed in the X-Forwarded-For HTTP request header for all IP address-related features, including connection/bandwidth throttling, access control, and IP geolocation.

This feature is useful if your web server is behind a load balancer or a proxy server. If you select "Trusted IP Only", then X-Forwarded-For IP will be used only when the request is coming from trusted IPs defined in the server-level Allowed List.
Syntax: Select from drop down list
Administrator EmailGo to top
Description: Specifies the server administrator's email address(es). If specified, administrators will be notified by email of important events (for example, when the LiteSpeed service is restarted automatically due to crash detection or when license is expiring).
Syntax: Comma delimited list of email address.
Tips: Email alert feature will only work if the server has an active MX server such as postfix, exim, or sendmail.
Index FilesGo to top
Description: Specifies names of index files that will be searched sequentially when a URL is mapped to a directory. You can customize it at the server, virtual host, and context level.
Syntax: Comma delimited list of index file names.
Tips: [Performance] Only set index files that you need.
Auto IndexGo to top
Description: Specifies whether to generate a directory index on the fly when index files listed in Index Files are not available in a directory. This option is customizable at the virtual host and context level, and is inherited along the directory tree until it is explicitly overridden. You can customize the generated index page. Please check online wiki How-tos.
Syntax: Select from radio box
Tips: [Security] It is recommended to turn off Auto Index wherever possible to prevent revealing confidential data.
See Also: Index Files, Auto Index URI
Auto Index URIGo to top
Description: Specifies the URI that will be used to generate the index page when index files listed in Index Files are not available in a directory. LiteSpeed web server uses an external script to generate the index page providing the maximum customization flexibility. The default script produces an index page with same look as Apache's. To customize the generated index page, please read online wiki How-tos. The directory to be indexed is passed to the script via an environment variable "LS_AI_PATH".
Syntax: URI
See Also: Index Files, Auto Index
Enable ExpiresGo to top
Description: Specifies whether to generate an Expires header for static files. If enabled, an Expires header will be generated based on Expires Default and Expires By Type.

This can be set at server, virtual host and context level. Lower level settings will override higher level ones, i.e. context settings will override virtual host settings and virtual host settings will override server settings.
Syntax: Select from radio box
Expires DefaultGo to top
Description: Specifies default settings for Expires header generation. This setting takes effect when Enable Expires is set to "Yes". It can be overridden by Expires By Type. Do not set this default at the server or virtual host level unless you have to, since it will generate Expires headers for all pages. Most of time this should be set at the context level for certain directories that do not change often. If there is no default setting, no Expires header will be generated for types not specified in Expires By Type.
Syntax: A|Mseconds
The file will expire after base time(A|M) plus specified seconds. Base time "A" sets the value to the client's access time and "M" to the file's last modified time.
Expires By TypeGo to top
Description: Specifies Expires header settings for individual MIME types.
Syntax: Comma delimited list of "MIME-type=A|Mseconds". The file will expire after base time (A|M) plus specified seconds.

Base time "A" sets the value to the client's access time and "M" to the file's last modified time. MIME-type accepts wildcard "*", like image/*.
IP to Geolocation DBGo to top
Description: Multiple MaxMind geolocation databases can be specified here. MaxMind has the following type of DBs: Country, Region, City, Organization, ISP and Netspeed. If multiple databases of types "Country", "Region", and "City" are configured, the last one will be effective.
DB File PathGo to top
Description: Specifies the path to MaxMind GeoIP database.
Syntax: file path
DB Cache TypeGo to top
Description: Specifies what kind of cache mode should be used. Cache modes are: Standard, MemoryCache, CheckCache and IndexCache. MemoryCache is recommended and is the default.
Syntax: Select from drop down list
File NameGo to top
Description: Specifies the path for the log file.
Syntax: File name which can be an absolute path or relative to $SERVER_ROOT.
Tips: [Performance] Place the log file on a separate disk.
Log LevelGo to top
Description: Specifies the level of logging to include in your log file. Available levels (from high to low) are: ERROR, WARNING, NOTICE, INFO and DEBUG. Only messages with level higher or equal to the current setting will be logged.
Syntax: Select from drop down list
Tips: [Performance] Using DEBUG log level does not have any performance impact, unless Debug Level is set to a level other than NONE. It's recommended to set Log Level to DEBUG and Debug Level to NONE. These settings mean that you will not fill up your hard disk with debug logging, but you will be able to use the Toggle Debug Logging action to control debug output. This action can turn debug logging on and off on the fly, and is useful for debugging busy production servers.
See Also: Debug Level
Debug LevelGo to top
Description: Specifies the level of debug logging. Log Level must be set to DEBUG to use this feature. Debug logging is disabled when "Debug Level" is set to NONE even if Log Level is set to DEBUG. Toggle Debug Logging can be used to control debug level on a live server without restarting.
Syntax: Select from drop down list
Tips: [Performance] Important! Always set this to NONE if you do not need detailed debug logging. Active debug logging will severely degrade service performance and potentially saturate disk space in a very short time. Debug logging includes detailed information for each request and response.

It's recommended to set Log Level to DEBUG and Debug Level to NONE. These settings mean that you will not fill up your hard disk with debug logging, but you will be able to use the Toggle Debug Logging action to control debug output. This action can turn debug logging on and off on the fly, and is useful for debugging busy production servers.
See Also: Log Level, Toggle Debug Logging
Rolling SizeGo to top
Description: Specifies when the current log file needs to be rolled over, also known as log rotation. When the file size is over the rollover limit, the active log file will be renamed to log_name.mm_dd_yyyy(.sequence) in the same directory and a new active log file will be created. The actual size of the rotated log file once it is created will sometimes be a little bigger than this size limit. Set to 0 to disable log rotation.
Syntax: Integer number
Tips: Append "K", "M", "G" to the number for kilo-, mega- and giga- bytes.
Enable stderr LogGo to top
Description: Specifies whether to write to log when receiving stderr output from any process started by the server. If enabled, stderr messages will be logged in the same directory as the server log with the fixed name "stderr.log". If disabled, all stderr output will be discarded.
Syntax: Select from radio box
Tips: Turn it on if you need to debug configured external applications: i.e. PHP, Ruby, Java, Python, Perl.
File NameGo to top
Description: Specifies the file name of the access log file.
Syntax: File name which can be an absolute path or relative to $SERVER_ROOT.
Tips: [Performance] Put access log file on a separate disk.
Piped LoggerGo to top
Description: Specifies the external application that will receive the access log data sent by LiteSpeed through a pipe on its STDIN stream (file handle is 0). When this field is specified, the access log will be sent only to the logger application and not the access log file specified in previous entry.

The logger application must be defined in External Application section first. Server-level access logging can only use an external logger application defined at the server level. Virtual host-level access logging can only use a logger application defined at the virtual host level.

The logger process is spawned in the same way as other external (CGI/FastCGI/LSAPI) processes. This means it will execute as the user ID specified in the virtual host's ExtApp Set UID Mode settings and will never run on behalf of a privileged user.

LiteSpeed web server performs simple load balancing among multiple logger applications if more than one instance of a logger application is configured. LiteSpeed server always attempts to keep the number of logger applications as low as possible. Only when one logger application fails to process access log entries in time will the server attempt to spawn another instance of the logger application.

If a logger crashes, the web server will start another instance but the log data in the stream buffer will be lost. It is possible to lose log data if external loggers cannot keep up with the speed and volume of the log stream.
Syntax: Select from drop down list
Log FormatGo to top
Description: Specifies the log format for the access log. When log format is set, it will override the Log Headers setting.
Syntax: String. The syntax of log format is compatible with Apache 2.0's custom log format.
Example: Common Log Format (CLF)
"%h %l %u %t \"%r\" %>s %b"

Common Log Format with Virtual Host
"%v %h %l %u %t \"%r\" %>s %b"

NCSA extended/combined log format
"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\"

Log cookie value of Foobar
"%{Foobar}C"
See Also: Log Headers
Log HeadersGo to top
Description: Specifies whether to log HTTP request headers: Referer, UserAgent, and Host.
Syntax: Select from checkbox
Tips: [Performance] Turn this off if you do not need these headers in the access log.
See Also: Log Format
Keep DaysGo to top
Description: Specifies how many days the access log file will be kept on disk. Only rotated log files older than specified number of days will be deleted. The current log file will not be touched regardless how many days' data it contains. If you do not want to auto-delete stale and very old log files, set this value to 0.
Syntax: Integer number
Compress ArchiveGo to top
Description: Specifies whether to compress rotated log files in order to save disk space.
Syntax: Select from radio box
Tips: Log files are highly compressible and this is recommended to reduce disk usage for old logs.