At a Glance

Catalog

System

Category

Web Servers

User volumes

yes

Min. memory

736 MB

OS

Linux

Constraints

no

Questions/Comments

Ask Forum

Resource

Minimum

Maximum

Default

CPU

0.5

80

0.6

Memory

768 MB

160 GB

800 MB

Bandwidth

5 Mbps

10 Gbps

800 Mbps

Name

Dir

Protocol

Description

in

in

http

Serves HTTP requests coming from web clients. Serves the HTTP/1.1 and 1.0 protocols.

ctl

in

http

Control terminal that is used for enabling/disabling the outputs and retrieving output terminal state from load-balancer.

ui

in

http

Exposes a Web UI that contains load-balancer runtime statistics.

db

out

mysql

Access to a MySQL server. Usage is defined by whatever scripts reside on the content volume (if any). This terminal may be left unconnected if it is not used.

fs

out

nfs

Access to a network file system for shared file storage, providing read-write file access over NFS. Usage is defined by whatever scripts reside on the content volume (if any). Software on the content volume sees the mounted remote file system as /mnt/fs in the appliance's filesystem space. This terminal may be left unconnected if it is not used. The connected server must have a read-write share named /mnt/data.

log

out

cifs

Access to a CIFS-based network file system for storing access and error logs. This terminal may be left unconnected if it is not used. The connected server must allow anonymous logins and have a read-write share named share.

aux

out

any

Access to an SMTP server for sending outgoing e-mail. Usage is defined by whatever scripts reside on the content volume (if any). Note that 'sendmail' is not configured on the appliance, any application that needs to send mail, should simply use SMTP directly, using 'aux' as the target hostname. For Perl CGI scripts the Mail::Mailer module can be used to do that.
This terminal may be left unconnected if it is not used.

net

out

any

Gateway output for subnet access.
This terminal may be left unconnected if it is not used.

mon

out

cce

Sends performance and resource usage statistics.
This terminal may be left unconnected if it is not used.

Volume

Description

content

Read-only, shareable volume providing the web content (documents, media and scripts) to be served by WEBx4.

Property name

Type

Description

host_name

String

Host name of the website. WEBx4 uses this name to display in automatically generated pages, as well as for constructing absolute URLs, for example, in server-generated redirects (for example, as may be set up in a custom config file installed on the content volume). Note: Although explicit redirects are rarely configured, a request for a directory without the trailing '/' causes a re-direct to be issued to the client, with the '/' appended; this redirect will use the value of host_name if it is set.
Setting this property correctly is recommended if WEBx4 is expected to be accessed by older clients that do not send a Host: header with their HTTP requests.
If this property is set to an empty string, the host name used in the client's request is used.
Default: (empty)

admin_email

String

E-mail address for the server administrator. WEBx4 uses this name to display it in automatically generated pages.
Default: root@localhost

content_on_fs

String

Specifies whether the content is relative to the file system at the fs terminal or is on the content volume. Allowed values are on and off. If set to on, all content is relative to the file system at the fs terminal. If set to off, the content is on the content volume.
Default: off

docs_dir

String

Root directory on the content volume where the documents to be served are located. For example, it may be /mydocs. If docs_dir is set to the empty string, the root directory of the content volume is used.
The directory must be pre-existing on the content volume.
Default: (empty)

docs_loc

String

An optional location within the client-visible namespace where the content should appear ("client-visible namespace" is the path portion of a URL, or what appears to the right of the host name in a URL, including the leading /). If set to a non-empty value, this becomes the namespace root, as seen by the client, where the document root directory appears. For example, if docs_loc is set to subspace/samples, an HTTP request for /subspace/samples/file1.html will serve file1.html from the document root directory. Note that a request for a location outside /subspace/samples will return an error, except if it is a request for a script in the scripts directory (see scripts_loc).
This property is useful when WEBx4 serves a subspace of a Web site. Do not append a trailing slash to this value.
Default: (empty)

scripts_dir

String

Root directory on the content volume where CGI scripts are located. For example, it may be /scripts. This should be set to a non-empty value, referring to a directory on the content volume that contains only executable scripts (don't set it to "/").
The directory must be pre-existing on the content volume.
Default: (empty)

scripts_loc

String

The location in the web space where the scripts directory specified by scripts_dir should be visible. This must be set to a non-empty string to enable the use of a dedicated scripts directory. A typical value may be /cgi-bin. Do not append a trailing slash to this value.
Default: (empty)

logs_enabled

String

Controls whether WEBx4 will send its logs out the log terminal. Allowed values are on and off. If set to on, the log terminal must be connected. If this is set to off, no access log is used at all and the error log is written to a file on the root filesystem of the WEB servers, rotated weekly, with 4 weeks of back logs kept (/var/log/httpd/error_log*). Default: off

logs_base_dir

String

Directory where WEBx4's logs are stored. This property has no effect if logs_enabled is set to off. Default: /

error_log_level

String

Severity level of messages to be written to the error log. Allowed values are debug, info, notice, warn, error, crit, alert and emerg. debug writes most messages, emerg writes only emergency messages. Default: warn

srv2_standby

Integer

Specifies whether the second WEB5 server is in standby mode. If non-zero, the second WEB5 server is in standby mode, otherwise it is not in standby mode.
Default: 1

srv3_standby

Integer

Specifies whether the third WEB5 server is in standby mode. If non-zero, the third WEB5 server is in standby mode, otherwise it is not in standby mode.
Default: 1

srv4_standby

Integer

Specifies whether the fourth WEB5 server is in standby mode. If non-zero, the fourth WEB5 server is in standby mode, otherwise it is not in standby mode.
Default: 1

timezone

String

Specifies the time zone used in the appliance. If this property is empty, the timezone is not modified and left as-is. A list of supported time zones is available here. Default: empty

Property name

Type

Description

lb_mode

String

Specifies the mode of operation and a way to use the named session cookie for session identification. Valid values are:
passive - the cookie is not modified. It is expected that a given cookie value is always unique and the same value is never used by another server.
sync - the cookie string in the HTTP response from a server is modified to make it unique to the terminal from which the response came (by adding a 4-character terminal ID into the cookie value). The 'terminal ID' is stripped before a request is forwarded to a server on one of the outX terminals. Other than inserting the terminal ID, the mapping between cookie values and output terminals is the same as for passive - that is, the entire cookie value is compared.
insert - the load balancer itself inserts a cookie into responses sent back to the client on in , so when the client sends subsequent requests with that cookie, they are directed to the same server as the first request from that client. The cookie inserted by HALB is without an expiration date, meaning that it is not to be permanently saved by the client software.
source - The source IP address of the request is used to bind the session to a particular backend web server. The cookie property is ignored.
Default: passive.

lb_cookie_name

String

The name of the cookie used to identify a session. For the passive modes ( passive and sync - see the mode property below), this is the name of the cookie used by the back-end servers connected to out1 - out4 to identify client sessions. For the insert mode, this is the name of the cookie that HALB should insert into HTTP responses in order to make each client stick with a single server. If this property is set to the empty value, no session tracking is done and all requests are distributed in a simple round-robin fashion. Ignored for the source mode.
Default: (empty).

lb_cookie_check_length

Int

Defines how many bytes from the value of cookie are used as unique key in passive mode of operation to match session to backend web server. Default value of 10 is usually sufficient for all common php and java applications. This value must always be equal or less than the length of the cookie value.
Default: 10.

lb_max_connections

integer

The maximum number of concurrently active connections that the load balancer handles. When this number is reached, new connections are still accepted, but their processing is delayed until another connection is closed. Upon start, load-balancer automatically determines the maximum number of connections based upon available memory, compares it to the value of this property and uses the lowest value. If this property equals 0 then the computed value is used. Note that neither the available memory nor an explicit setting of this property have a direct effect on the balancer's throughput or its maximum request rate - setting a low number (or having little memory) affects response only if the back-end servers are performing lengthy operations for each request (for example, database searches), causing many requests to remain open at the same time.
Default: 0

lb_backup_outputs

String

A space or comma delimited list of outputs ( out1 - out4 ) that are considered backups. Traffic is directed to the backup servers only if all backend servers are unavailable. The purpose of these backup servers is to notify clients that something is wrong or redirect them, instead of throwing errors from unavailable backend or timing out.
Default: (empty).

lb_healthcheck_url

String

The URL used to perform the health check of the backend web servers in http_get and http_head health check methods. May be specified as a complete URL (http://host.name/file/to/check/for.php) or as a relative path (/file/to/check/for.php). If specified as a URL, HALB uses the HTTP/1.1 protocol while performing the health checks using the hostname extracted from UR, in a Host: header. This allows usage of virtual hosts. If specified as a relative path, HALB uses the HTTP/1.0 protocol and checks for the document specified by this property. If this property is empty, load-balancer checks for the default root '/' using the HTTP/1.0 protocol.
Default: (empty).

lb_healthcheck_agent

String

The string used as an agent identifier for http_get and http_head health check methods. If empty, "HALB-health-check" is used.
Default: (empty).

lb_healthcheck_method

String

The method used for the health check of the backend web servers.
tcp_connect - load-balancer connects to port 80 of the web server. If the connection is successfully established, load-balancer assumes that the web server is functional. This is the fastest method and requires the least resources.
http_head - load-balancer uses the HEAD method to request the document specified by the lb_healthcheck_url property. This is slower than tcp_connect, requires more resources on both load-balancer and web servers, but is more reliable. A status code of 2xx or 3xx, received from a web server, validates the server as operational.
http_get - load-balancer uses the GET method to request the document specified by the lb_healthcheck_url property. This is the slowest method that requires most resources but is most reliable.A status code of 2xx or 3xx, received from a web server, validates the server as operational. If the lb_healthcheck_regexp property is defined, then load-balancer downloads the document including all HTTP headers and server status code, and check for matches with the lb_healthcheck_regexp value. If match is found, then the backend server is considered functional, or is disabled if no matches were found.
Default: tcp_connect.

lb_healthcheck_regexp

String

A test string used with the http_get health check mode. Short or common values (eg. OK) will likely cause false positive matches. This string is a perl regular expression, more details about perl regular expressions are available here.
Default: (empty).

lb_healthcheck_interval

Int

Interval between health checks of the backend web servers (specified in seconds).
Default: 20 seconds.

lb_timeout

integer

Timeout in seconds to expire inactive sessions. If set to zero, inactive sessions do not expire. If set to a non-zero value, inactive sessions resumed after timeout seconds are considered stale, and requests bearing the 'forgotten' cookie are treated as if they have no cookie at all and are directed to a random server, using the usual round-robin method. This property is only valid for passive mode and ignored for all other modes.
Default: 0

lb_client_timeout

Int

Timeout in seconds for waiting for a request from a client after establishing the connection.
Default: 150.

lb_server_timeout

Int

Timeout in seconds for waiting for a reply from a backend web server after establishing the connection.
Default: 150.

lb_conn_timeout

Int

Timeout in seconds for establishing any tcp connection. This includes the health checks. Extra attention must be paid to this setting, because if under high load the health checks time out because of insufficiently small value, load-balancer starts to disable outputs. It is not recommended to set it lower than 20 seconds.
Default: 20.

lb_username

String

Username for accessing the load-balancer GUI through the ui terminal. If empty, there is no authentication.
Default: (empty).

lb_password

String

Password for accessing the load-balancer GUI through the ui terminal. Password is ignored if username is empty.
Default: (empty).

lb_ctl_port

Int

Port that is used to access the web service control interface through the ctl terminal.
Default: 80.

lb_ui_port

Int

Port that is used to access the load-balancer runtime statistics GUI through the ui terminal.
Default: 80.

cgi_ext

String

Defines the file name suffixes for CGI scripts as a space-separated list. This is used to specify which files to treat as executable CGI scripts (in any directory) and can be used as an alternative to specifying a common scripts directory - see the scripts_dir and scripts_loc properties. Default: .cgi

shared_perl_ext

String

Defines the file name suffixes for in-process Perl scripts as a space-separated list. This is used to specify which files to treat as Perl scripts to be run with mod_perl. Any extension that matches one already specified in cgi_ext overrides the use of CGI for that extension and configures it to be run by mod_perl instead. The in-process Perl module is configured to run scripts with the specified extensions in CGI compatibility mode - most Perl scripts designed to be run as CGI processes should work if set up as in-process scripts as well. Note: it is important to check your scripts for proper initialization of all file-scope variables, for example, with use strict; use warnings; , since all scripts run by mod_perl execute without re-starting the Perl interpreter. If unsure whether your scripts will work with mod_perl, review the mod_perl documentation for more information: http://perl.apache.org/docs/index.html.
Default: (empty) (that is, don't use mod_perl)

index_files

String

Ordered, space-separated list of files to use as a directory index page in case the client requests a URL that refers to a directory name.
Default: index.html index.html.var

use_htaccess

String

Specifies whether to enable the use of .htaccess files for the entire document tree. This is disabled by default and should be used only if you have a content directory structure that requires fine-grain control of server options, but is too complicated to configure using a set of sections in a common config file, or if you have a pre-configured content volume that already uses .htaccess and want to avoid the hassle of re-arranging it. If config options are needed only for the document root itself, put your settings in the document root directory in the .htconf file instead - they will be applied exactly the same way as for .htacces, except the file is read once at boot time. Default: off

max_connections

Integer

Maximum number of concurrent active connections that each WEB5 server can handle. If this limit is reached, additional connection requests are queued (up to a limit of 511) and processed as currently active connections get closed. This value should be raised only if WEBx4 is expected to serve a large number of requests that need access to a slow external source of data (for example, lengthy database queries). The actual number of concurrent connections may be limited below the value set for this property, if there is not enough system memory. See the Memory Usage section. The max_connections value cannot be set to more than 256.
Default: 128

persistent_connections

String

Controls whether WEBx4 allows clients to request more than one document on the same connection. Allowed values are on, off. You may need to disable the persistent connections only if you have problems with clients that do not support HTTP/1.1 properly but don't fall back to HTTP/1.0. Default: on

idle_timeout_sec

Integer

Timeout, in seconds, for keeping a client connection open if there is no request or response going through. This property is used only if persistent_connections is on. Keeping this timeout short helps drop forgotten connections quickly. Default: 15

data_timeout_sec

Integer

Timeout, in seconds, for receiving or sending more data if a data transfer has started but is not completed. Having this timeout allows WEBx4 to drop connections that got forgotten, while still allowing delays during the transfer. Default: 300

default_charset

String

Default character set to report for returned documents of type text/html or text/plain. The property should be set either to the name of a character set or to off (to disable sending of a charset header in HTTP responses). For some browsers setting this property can override the character set value provided by the author of the served HTML documents and is therefore recommended only if there are documents that do not contain a valid character set specification and it is known in advance that all documents served by WEBx4 are in the same character set. Typical example values may be iso-8859-1 or utf-8. Default: Off
Note: To cover for special cases, including old CGI scripts that do not generate a proper content-type meta tag, per-directory setting of the default charset is possible using custom configuration files stored on the content volume.

info_level

String

Controls how much information WEBx4 discloses about itself to web clients (in HTTP responses and in automatically generated pages). Allowed values are full (most info), os, minor, major, prod (least info). As a security measure, it is recommended that you disclose the minimum information. Default prod

server_signature

String

Controls whether WEBx4 appends a server signature line at the bottom of all generated pages (for example, on error pages). Allowed values are on, off. The amount of information WEBx4 includes in the signature is controlled by info_level. Default off (no signatures).

env

String

Used to pass settings to WEBx4 as name=value pairs. Default: (empty)