LiteSpeed Web Server Users' Manual

Version 5.1 Rev. 1

Server Log

Table of Contents

Server Log

File Name | Log Level | Debug Level | Rolling Size (bytes) | Enable stderr Log | Enable AIO Logging | 

Access Log

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

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 Size (bytes)Go 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.
Enable AIO LoggingGo to top
Description: Specifies whether to enable AIO logging for server log and access log. If enabled, asynchronous I/O will be used for writing log messages.
Syntax: Select from radio box
Tips: Enabling AIO logging can help overall server performance when server I/O wait is high.
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: Enterprise Edition Only 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.