 |
» |
|
|
|
You must install the Zeus web server before you run the setup
script. If you re-install the Zeus web server, you must re-run the
setup script. The setup script configures and enables WebQoS for all virtual
servers. The setup script enables NSAPI and HTACCESS for each virtual
server and creates the necessary directory and configuration files
for NSAPI. The Zeus NSAPI process user and group are the same as
those configured for the Zeus web server (which were configured
when you initially installed the Zeus web server). Running the setup.zeus Script | |
To run the setup script, as user root, type the following: cd /opt/webqospk
./setup.zeus [-p]
The -p option automatically configures the user (hpacadmin) and password (hpacadmin) of the HP WebQoS Settings administration web page
for each virtual server. If the -p option is not specified, you
are prompted to enter the user and password for the HP WebQoS Settings administration
web page for each virtual server. If you specify the -p option, HP recommends that you change
the password. Refer to “Changing the Password of the HP WebQoS
Settings Administration Web Page” in this section
for more information. While running the setup script, at the Root pathname of Zeus server prompt, enter the Zeus home directory (the default
is /usr/local/zeus). The setup script automatically configures and enables HP WebQoS. Default values set for all applicable configuration parameters
are listed in “HP WebQoS Configurable Parameters
for Zeus”. You can also run the setup script by typing ./setup from the /opt/webqospk directory. This script prompts you for the type
of web server (Netscape or Zeus) that you are configuring. The following is an example of running the setup.zeus script. In this example, the Zeus web server is
installed in the default /usr/local/zeus home directory and two virtual servers (server1 and server2) have been configured. User input is in bold. Note that when the password is entered, it does not
appear on the screen. Root pathname of Zeus server (/usr/local/zeus): |
Updating server server1 at /usr/local/zeus/ns-config/https-server1 ...
Enter admin name for HP WebQoS Peak Configuration. (hpacadmin): admin1 |
Choose a password for admin1:
Enter the password again:
VirtualServer server1 - Success
Successful stop on backend machine localhost |
VirtualServer server1 - Success
Successful start on backend machine localhost |
Updating server server2 at /usr/local/zeus/ns-config/https-server2 ...
Enter admin name for HP WebQoS Peak Configuration. (hpacadmin): admin2 |
Choose a password for admin2:
Enter the password again:
VirtualServer server2 - Success
Successful stop on backend machine localhost |
VirtualServer server2 - Success
Successful start on backend machine localhost |
Changing the Password of the HP WebQoS
Settings Administration Web Page | |
To change the default password (hpacadmin) configured by the setup script, for each virtual
server, type
$ZEUSHOME/web/bin/htpasswd doc_root/hpac/adminfile hpacadmin new_password where $ZEUSHOME is the Zeus home directory (the default is /usr/local/zeus), doc_root is the documentation root of the virtual server
for which you are changing the password, hpacadmin is the name of the user whose password is being
changed, and new_password is the new password assigned to the user. For example, if you want to change the password of the hpacadmin user of virtual server server1 to qosserver1 and the Zeus home directory is /usr/local/zeus and the documentation root is /webpages/server1, type the following: /usr/local/zeus/web/bin/htpasswd /webpages/server1/hpac/adminfile hpacadmin qosserver1 If the user does not exist in adminfile, it is added to the file. Otherwise, the existing
password for the user is overwritten. If you want to modify the user, you can edit adminfile. However, you must use htpasswd to modify the password. You must have write permission for adminfile in order to change the password using the htpasswd command. Setting the HP WebQoS Configurable Parameters for Zeus | |
You can edit the configuration parameters in two different
ways: You can access the HP WebQoS
Settings administration web page at the URL http://system_name:port_number/hpac. Your Zeus server must be running to access this
page. Use the username and password you configured (either from
the setup script or by using the htpasswd command) to access this page. Select Control to
get to the Settings administration web page. You can edit the configuration file $ZEUSHOME/ns-config/https-server_name/config/hpac/config.ac Refer to “HP WebQoS Configurable Parameters
for Zeus” for a list of the available
configurable parameters for the Zeus server.
The following is an example of the "HP WebQoS" page: The following sections describe the parameters that can be
set using the HP WebQoS Settings administration
web page. “HP WebQoS Configurable Parameters
for Zeus” for a list of the available configurable
parameters for the Zeus server and a list of defaults already configured
in config.ac. For the default value, the load threshold is set to 2. Table 4-1 HP WebQoS for Zeus Configurable Parameters: Admit Sessions | Parameter | Description |
|---|
| Shutdown | After the specified number of seconds, do not
admit any new sessions and reject all remaining sessions. | | Always | Disable HP WebQoS and admit all sessions to
the web server. If you are permanently disabling HP WebQoS, you should
remove HP WebQoS from your system (see “Removing HP WebQoS for Zeus” for
more information). | | Load | If the load is less than this specified amount,
admit the session. The load threshold works best when a web application
is processor-intensive. |
To calculate the load threshold, do the following: Run the top command. Note the first listed “Load averages” and
the percentage listed under “IDLE” of “Cpu states.” Example 4-1 Sample Output from the top Command System: web_server Wed Apr 22 10:41:59 1998
Load averages: 1.45, 1.46, 1.78
149 processes: 145 sleeping, 3 running, 1 stopped
Cpu states:
LOAD USER NICE SYS IDLE BLOCK SWAIT INTR SSYS
1.45 100.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% |
If IDLE is greater than zero, then set the threshold
to
(100 - IDLE)/100. If IDLE equals zero, then set the threshold to the first listed
load average. Using the above sample output, you would set the load threshold
to 1.45.
Run top when performance is poor and acceptable to determine
an acceptable load level. For the default, the interval between requests is set to 600
seconds (10 minutes) and the session duration is disabled. Table 4-2 HP WebQoS for Zeus Configurable Parameters: End Sessions | Parameter | Description |
|---|
| Interval between requests | The amount of time, in seconds, between requests
within the session. If the time between requests exceeds the specified threshold,
the session is ended. | | Session duration | The amount of time of the session. If the session
exceeds the specified threshold, the session is ended. Set this
parameter to zero to disable this threshold. |
Respond to Rejected SessionsRejected sessions can either be redirected or served a web
page containing a standard error message or other information. If redirection is disabled or the redirect request is not
accepted, a web page containing a standard error message or other
information is returned. The default is to disable redirection and serve an error page
to a rejected session. Table 4-3 HP WebQoS for Zeus Configurable Parameters: Redirect Rejected
Sessions | Parameter | Description |
|---|
| Disable | Do not redirect the rejected session. Instead,
return a web page with an error message or other information. | | Address | Redirect the rejected session to a load balancing
system (such as a cluster manager), to another web server, or to another
system set up to specifically handle rejected sessions. Specify
the full domain name or IP address. | | Cluster | Redirect the rejected session to a randomly
selected member of a cluster. | | Domain | Redirect the rejected session to the domain
to which the systems in the cluster belong. For example, if the
cluster consists of the two systems ww1.sales.acme.com and ww2.sales.acme.com, specify the domain as .sales.acme.com. Note the leading dot.
The
domain specifies the scope over which the client-side cookies can
be shared (HP WebQoS uses client-side cookies to encode session
information). | | Group | The cluster group to which this system belongs. | | TTL | Time to Live. The number of redirections allowed
before rejecting the session. Add one to the TTL parameter to get the
number of redirects. For example, setting the TTL to 0 allows one
redirection. Setting the TTL to 1 allows two redirections.
It
is recommended that the TTL be set to a value no larger than 2. |
When redirection is disabled, the following types of web pages
can be served: Table 4-4 HP WebQoS for Zeus Configurable Parameters: Respond to Rejected
Sessions | Parameter | Description |
|---|
| Error | The “Error 503 Service Unavailable” error
message is served to rejected requests. This is the easiest but
least informative way to respond to a rejected request. Extra load
on the system may be generated by users trying to immediately re-establish
a connection. | | Page | The specified web page is served to rejected
requests. You can provide information to the customer such as why
the session was rejected and when would be a more opportune time
to return to the site. A user is less likely to try immediately re-establishing
a connection and more likely to return to the site. | | Allocate sessions | A countdown web page
is served to rejected requests. The user is asked to wait a certain
amount of time before getting access to the site. This type of session
is given priority over new sessions.
Enter the
number of sessions you wish to have admitted each minute. For example,
if you allocate five sessions per minute, one session will be admitted
every 12 seconds. If seven sessions are rejected, five will be admitted
the next minute and two will be admitted the minute after. Make
sure the allocation rate is less than the system's capacity.
You
may want to compensate the allocation for no-shows.
Monitoring
the % Priority Requests statistic will show the
system's load due to priority sessions. Reduce the allocation
rate if the number approaches or is over 50%.
Also
monitor the Last Allocation Delay statistic.
It shows how long a deferred user waited before his/her session was
admitted. | | External | Use an external function or application. For
example, the user could be offered a discount or other incentive
to return to the site; or, the user could be offered to enroll in
a service plan that guarantees access to the site. Currently, no
supported functions or applications exist. If selected, the Error
page is returned. | | Exclude | After the initial rejection, the user is prevented
from returning to the site after the specified amount of time (in
seconds). This discourages a user from trying to immediately re-establish
a connection.
If a session is allocated, this
is the minimum delay that can be scheduled. |
Creating an Allocation Page for Rejected SessionsThe following is the default allocation page served to the
user: Example 4-2 Server Busy We are sorry our server is busy, and in order to ensure adequate levels of service to our current visitors, we cannot serve you at this time. We have allocated you a position in line and will serve you as soon as we can. |
You will automatically enter the site in 1:23 (minutes:seconds). |
To change the content of this page, you must edit the file $ZEUSHOME/ns-config/https-server_name/config/hpac/config.ac To change the “Server Busy” title, edit the deferral.title parameter. To change the content of the message, edit
the deferral.message parameter. To edit the countdown line, edit the deferral.enterMsg parameter. Note that each parameter is ended by a single
period on its own line. The default allocation page would include the following entries
in the config.ac file: deferral.title
Server Busy
.
deferral.message
We are sorry our server is busy, and in order to ensure adequate levels of service to our current visitors, we cannot serve you at this time. We have allocated you a position in line and will serve you as soon as we can.
.
deferral.enterMsg
You will automatically enter the site in
. |
Starting HP WebQoS for Zeus | |
HP WebQoS is enabled after you have installed it (provided
you have met certain conditions; see “Configuring HP WebQoS for Zeus” for more
information) or run the setup script (see “Running the setup.zeus Script” for
more information). If you have stopped HP WebQoS, then you can start it again
by configuring and specifying the load from the HP WebQoS
Settings administration web page. Stopping HP WebQoS for Zeus | |
To stop or disable HP WebQoS, set the Admit Session to “Always” from the HP
WebQoS Settings administration web page. If you are permanently stopping HP WebQoS, you should remove
HP WebQoS from your system (see “Removing HP WebQoS for Zeus” below for
more information). Removing HP WebQoS for Zeus | |
You can remove HP WebQoS from one to all virtual servers. To remove HP WebQoS from one or more virtual servers, do the following: Type /opt/webqospk/setup.zeus -r At the Root pathname of Zeus server prompt, enter the Zeus home directory. For each virtual server, you are prompted to remove
HP WebQoS from it. Enter y to remove HP WebQoS from it or n to keep HP WebQoS installed on it.
To remove HP WebQoS from all virtual servers, do the following: Type /opt/webqospk/setup.zeus -R At the Root pathname of Zeus server prompt, enter the Zeus home directory.
You can also use the /opt/webqospk/setup script which prompts you for the type of web server
(Netscape or Zeus) you want to remove. The following is an example of removing HP WebQoS from one
of two virtual servers configured on the system (remove HP WebQoS
from server2; keep HP WebQoS installed on server1). The web server
is installed in the default /usr/local/zeus directory. User input is in bold. Root pathname of Zeus server (/usr/local/zeus):
Remove AdmissionController from server server1 (y or n): n
Remove AdmissionController from server server2 (y or n): y
Uninstall HP WebQOS Peak for server server2 at /usr/local/zeus/ns-config/https-server2 |
Other Configuration Considerations | |
This section covers tasks beyond basic configuration. Tuning Your Web Server's CacheTo control session admissions, HP WebQoS tracks the session
state by including cookies in HTTP responses. For HP WebQoS to operate effectively,
the server cannot generate all of its responses from the cache. This
may cause the performance of the web server to be slow. However, you can tune the cache by configuring the $ZEUSHOME/ns-config/https-server_name/config/hpac/config.ac file to allow specified mime types to be cached
or not cached. For example, if you serve HTTP pages with embedded images,
you can cache the images by adding the following lines to the configuration
file: mime.cache
mime.type image/gif
mime.type image/jpeg |
Or, if your pages are generated by an application such as
an NSAPI plug-in or CGI script, you can allow all mime types to
be cached except for the mime types associated with the application.
For example, to cache all mime types except those generated by CGI
scripts, add the following lines to the configuration file: mime.nocache
mime.type magnus-internal/cgi |
You must restart the web server if you make changes to the
configuration file. If a page is not cachable, such as a dynamically created page
or other pages marked by NSAPI as uncachable, you cannot cache it
even if you specify it in the configuration file as cachable. Allowing Equal Access to a System's ResourcesIf a web server hosts multiple virtual web sites, HP WebQoS
can be configured to balance traffic between each site, allowing
each site to share the system's resources equally. The description or pattern of the web servers' document
roots for each virtual server must be configured in the $ZEUSHOME/ns-config/https-server_name/config/hpac/config.ac configuration file. HP WebQoS uses the isolate.pattern parameter to monitor each site's traffic.
You must restart the web server after editing the configuration
file. For example, a system is hosting two web sites for Company
A and Company B. Company A's home page is located at /web_pages/company_a/index.html and Company B's home page is located
at /web_pages/company_b/index.html. To monitor each site's traffic, add
the following to the configuration file: isolate.pattern /web_pages/%[^/] Refer to documentation on the sscanf command for more information on constructing the
pattern. After editing the configuration file, restart the web server. Detecting Failed Servers in a ClusterWhen a web server is running, it periodically broadcasts a
message that it is up. When a web server is shut down, it broadcasts
a message that is unavailable. When a web server is not running,
it does not broadcast a message. Each web server in a cluster listens for these broadcast messages.
Based on the messages received or not received, it will mark each
system as up or down. The web server marks a system as up when it receives the appropriate broadcast
message from that system. The web server marks a system as down
when it receives the appropriate message or it fails to receive
a message after a specified number of broadcast intervals. In the HP WebQoS $ZEUSHOME/ns-config/https-server_name/config/hpac/config.ac configuration file, you can configure how often
messages are sent (broadcast interval) and how many messages can
be missed before the system is marked as down. The parameters are: cluster.keepalive.interval 60
cluster.keepalive.misses 3 |
where the interval is measured in seconds. The values given
are the default values. If you configure these parameters, the web server must be
restarted. Also, all systems in the cluster should use the same
values for these parameters. Decreasing the broadcast interval decreases the time it takes
to detect a failure. However, it also increases broadcast traffic. Sometimes, not all broadcast messages are received. Therefore,
the number of misses should be set to a value greater than one.
However, in a large cluster, removing a machine falsely does not
severely impact the cluster's capacity and improves the
responsiveness to failures. The maximum time to detect a failure can be determined by
multiplying the broadcast interval by the number of misses. For
the default values, the maximum failure detection time is three
minutes. |
Printable version
