Regardless of the size of your organization, you should
include performance tuning as a regular part of administering servers.
By tuning the configuration settings of dispatcher and services,
you can optimize the speed and efficiency of IBM Cognos 8.
For users, optimal performance means that their reports run fast
and without errors. For you, it means that IBM Cognos 8
is stable and that the users are happy.
Ideally, you want to tune the servers to meet the user demand
at the peak usage times.
You may need to add dispatchers to your installation to meet
the demands of users. Or, you may need to distribute your installation
or upgrade the computer on which IBM Cognos 8 is installed.
For more information, see the Installation and
Configuration Guide and the Architecture
and Deployment Guide.
The level of logging 
can affect performance. When IBM Cognos 8
logs more detail, more resources are allocated to logging and fewer
resources are then available to run reports.
Before you change any settings, ensure that you tested dispatchers , and
reviewed the pertinent log messages . You should also understand your performance
requirements.
Ensure that your models are optimized for reporting. For more
information, see the Framework Manager User Guide.
How IBM Cognos 8 performs is tightly related to the
performance of the operating system of the computer where IBM Cognos 8
is installed. Therefore, it is important to ensure that your operating
system is tuned.
Tuning IBM Cognos 8 includes
If you intend to define routing rules for reports ,
you must set server group names for the dispatchers or configuration
folders to which you want reports to be routed.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
In the upper-left corner of the Scorecard pane,
click the arrow to view the Change view menu. Click All
dispatchers.
Tip: You can also set the server group property at the
system level.
Click the arrow for the Actions menu next to the dispatcher
and click Set properties.
Click the Settings tab.
Select Tuning from the Category list.
Type a name in the Value column for
the Server Group property.
Click OK.
You can use this server group name when you define routing rules.
If your installation includes more than one dispatcher,
you can specify the proportion of requests that each dispatcher
handles by changing their processing capacity. This is commonly referred
to as load balancing. You typically set the capacity for a dispatcher
based on the CPU speed of the computer where it is installed.
For example, a first dispatcher is installed on a 2 GHz computer
and a second dispatcher on a 1 GHz computer. You set the processing
capacity of the first dispatcher to 2.0 and the second to 1.0. The
first dispatcher handles two-thirds of the requests while the second
handles one-third of the requests. If you set the capacity of both
dispatchers to 1.0, requests are sent to each dispatcher alternately.
The default processing capacity for each dispatcher is 1.0.
Affinity settings take precedence over balance request settings.
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
Click the arrow for the Actions menu next to System and
click Set properties.
Tip: You can also change the processing capacity setting
at the dispatcher level.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type a new value
for the Processing capacity, and then click OK.
The new value takes effect immediately.
If your IBM Cognos 8 servers operate within
a load balancing infrastructure, you can turn off the weighted round
robin format of load-balancing for the dispatcher. Otherwise, load
balancing may be duplicated by the cluster and by IBM Cognos 8,
which can degrade performance.
You can set the dispatcher property named loadBalancingMode either
to weightedRoundRobin or clusterCompatible.
In weightedRoundRobin mode, the dispatcher sprays requests in
a weighted round fashion, according to the configuration settings
for the dispatcher . This is the default mode.
In clusterCompatible mode, non-affinity requests are processed
locally if possible. If there is no service on the local dispatcher,
the request fails. This ensures that IBM Cognos 8 respects
any load balancing performed by your own load-balancing infrastructure.
You can set the loadBalancingMode property for single dispatchers
or for a group of dispatchers in a configuration folder . Because
it is an inherited property, you can move dispatchers to a configuration
folder and set the loadBalancingMode property for the folder to quickly
set the property for a group of dispatchers.
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
Click the arrow for the Actions menu next to System and
click Set properties.
Tip: You can also change the load balancing setting at
the dispatcher level.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, select the value
for the Load Balancing Mode, either Weighted
Round Robin or Cluster Compatible, and then click OK.
The new value takes effect immediately.
Most organizations have a period of peak demand. This
period is usually during business hours when employees are at work
and run interactive reports. You can determine the start and end
hours of the peak demand period for your organization.
During the peak period, you may want to set the number of connections
and processes low enough so that jobs can run faster and
system resources can process interactive requests from users. During
the non-peak period, you can set the number of connections and processes higher
because demands on the system are lower.
The default peak period is from 07:00 to 18:00. The default number
of connections for each service during the peak period and during
the non-peak period is four.
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
In the upper-left corner of the Scorecard pane,
click the arrow to view the Change view menu. Click All
dispatchers.
Click the arrow for the Actions menu next to the dispatcher
and click Set properties.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type new values
for the following settings:
Tip: If you want to reset a configuration setting to its
default value, select its check box and click Reset to
default value.
Click OK.
For the report service, the batch report service, and
the data movement service, you can set the maximum number of processes
and the maximum number of high affinity and low affinity connections
that the dispatcher can open to handle requests. For the agent,
Content Manager, data movement, delivery, job, and report data services,
you can set the maximum number of connections.
There are separate settings for peak and non-peak hours .
There is a maximum of one of each of these services per dispatcher:
agent, Content Manager, data movement, delivery, job, report data.
Connections handle one request from one service at a time.
You can specify the maximum number of connections for each service
during peak periods and non-peak periods using the following settings:
The default number of connections is four.
There can be multiple report service, batch report service, and
data movement processes on each dispatcher. You can specify the
maximum number of processes during peak periods using the following
settings:
The default number of processes for each service is two.
In addition, report servers accept low and high affinity connections
to process requests from the batch report and report services. Servers
also accept low and high affinity connections to process requests
from the data movement service.
Low affinity requests can be handled by any report server. Typically,
low affinity requests are used when a report or data movement run
is initially requested.
High affinity requests are ideally handled by a specific report
server. Typically, high affinity requests are for reports that
were already requested and may include actions, such as going to the
next page in a report. If the specific report server is not available
or busy, then the report is rerun (low affinity request) on any
report server and the next page (high affinity request) is directed
to that server.
Affinity settings take precedence over balance request settings and
advanced routing settings .
If affinity settings are changed for a service while entries
are running, the number of server processes could double. The number
of processes may temporarily exceed the maximum setting while the
change takes effect. This may cause problems if your system does
not have enough memory for the interim period.
For more information about affinity connections, see the Architecture and Deployment Guide.
You can specify the number of low and high affinity connections
for the report service, the batch report service, and the data movement
service using the following settings:
- Number of high affinity connections
for the<service_name> during peak period
- Number of high affinity connections for the <service_name> during non-peak
period
For batch report service, the default number of low affinity
connections is two. For the data movement service and report service,
the default number of low affinity connections is four. The default
number of high affinity connections for all services is one.
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
In the upper-left corner of the Scorecard pane,
click the arrow to view the Change view menu. Click Services and
then click the service you want.
Click the arrow for the Actions menu next to the service
and click Set properties.
Tip: For report service and batch report service, you
can also set some settings at the system or dispatcher level.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type new values
for the processes and connections that you want to change.
Tip: If you want to reset a configuration setting to its
default value, select its check box and click Reset to
parent value.
Click OK.
You can specify the maximum number of seconds that interactive
requests made by users wait in the queue for an available report
service or data movement connection. If a request cannot be processed
within the time limit, the request fails and users receive an error
message.
If your operating system has adequate resources and IBM Cognos 8
is properly configured, requests should not take longer than the
time limit.
When you specify a time limit, consider the maximum number of
seconds that you want users to wait for a response. The default
queue time limit is 240 seconds.
Requests for the batch report service stay in the queue indefinitely.
If you have a high user load (over 165 users) and interactive
reports are running continuously in a distributed installation,
increase the queue time limit to 360 to avoid getting error messages.
You may also want to increase the asynchronous timeout setting to
avoid getting error messages. For more information, see the IBM
Cognos 8 Installation and Configuration Guide.
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
Click the arrow for the Actions menu next to System and
click Set properties.
Tip: You can also change the queue time limit settings
at the dispatcher or service level.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type a new value
for the Queue time limit of report service (seconds) or Queue
time limit of data movement service (seconds) setting.
Tip: If you want to reset a configuration setting to its
default value, select its check box and click Reset to
default value.
Click OK.
There are four settings for PDF files that together
determine the speed at which PDF files are created and the size
of PDF files.
The ideal settings are different for different environments.
For example, if you create PDF files as part of batch jobs overnight,
you may not care about speed. You may choose settings that create
small files that can be easily distributed but take longer to generate.
If you create ad hoc PDF files or complex PDF files with many charts
and graphics, you may care more about speed than file size.
You can use different PDF file settings for report service and
for batch report service.
PDF character encoding determines the character set that is used
to create PDF files. You can choose to use Windows1252 encoding,
the standard Windows single-byte encoding for Latin text in Western
writing systems, or unicode (UTF-16) encoding. By default, PDF character encoding
is determined automatically, based on the characters found in the
file.
The settings names are:
|
Windows1252 | If you know your files contain only Windows1252
characters, use this setting for faster PDF file creation. Any
unicode (UTF-16) character without a Windows1252 equivalent is converted
to an indeterminate Windows1252 character. |
Font | If you know your files contain non-Windows1252
characters (for example, Chinese characters), use this setting for
faster PDF generation than with the Auto setting. PDF built-in
fonts are all Windows1252 character encoded. Almost all other fonts
use the UTF-16 character set. This setting typically creates
larger PDF files than the Windows1252 setting. It is possible for
UTF-16 encoded files to gain better compression (see Content Compression Type). |
Auto | Use this setting to automatically determine
if Windows1252 or UTF-16 should be used to encode the text in the
document. If large bodies of text must be analyzed, this is
the slowest of the three settings. If speed is a concern you may
choose to try the other values with various reports to determine
the best setting for your environment. This is the default. |
To ensure that the fonts that areused in a report are available
to all readers, fonts can be embedded in PDF files. In IBM Cognos
Configuration, there are two font embedding lists, one for the report
service and one for the batch report service.
Fonts can be specified as always embedded or never embedded.
For example, fonts that you do not have a legal right to redistribute
may be specified as never embedded. Fonts that are not available
at your remote sales offices but are required to read PDF reports
may be specified as always embedded.
For more information about the font embedding lists, see the Installation and Configuration Guide.
In IBM Cognos Administration, you can allow
or disallow font embedding in report service and batch report service
PDF files. You can also choose automatic font embedding. Keep in
mind that files with embedded fonts are larger and take more time
to generate. Embedding fonts can cause a strain on network resources.
Fewer embedded fonts can reduce network resource consumption.
The license for some fonts prohibits embedding. Ensure that you
have permission from the vendor to embed licensed fonts.
The settings names are:
There are specialized fonts, such as bar-code fonts, that are
always embedded when used. These settings do not control embedding
of specialized fonts. PDF built-in fonts are never embedded.
|
Allow | If you know that your audience does not
have all the fonts they need to view PDF reports, use this setting.
Files are larger and PDF output is generated more slowly. Fonts
that are in the never embed list in IBM Cognos Configuration are prevented
from being embedded. This is the default. |
Disallow | If you know that your audience has all the
fonts they need to view PDF reports, use this setting. Files are
smaller and are generated faster. Fonts are not embedded unless
they’re in the always embed list in IBM Cognos Configuraiton. |
Auto | Automatically determines which fonts to
embed. This setting takes the longest time to generate PDF reports. If
the data contains only Windows1252 characters, both the always embed
and the never embed list in IBM Cognos Configuration are used. If
there is a conflict, the never embed list is used. Except
for specialized fonts, unlisted fonts are usually embedded only if
UTF-16 characters from that font are used in the file. |
You can set the compression type to use when PDF reports are
created. It takes longer to create PDF output for files with a higher
compression type but the resulting files are smaller.
The content compression type specifies which data is compressed.
The Content Compression Type specifies how much the
data is compressed. The combination of the two settings determines
the final file size.
The settings names are:
The choices for this setting, from lowest to highest compression
type, are: Classic, Basic, Improved, Advanced,
and Full. Classic is the
default.
Compression type refers to the amount of data that is compressed
within a PDF report. Typically, less compression means faster compression
and a larger document. Versions of the Adobe PDF Acrobat Reader
earlier than version 6.0 do not support compression types higher than
Classic.
There are rare cases where compression causes small files to
become slightly larger.
You can specify the compression algorithm level to use when PDF
files are created.
The content compression type specifies which data is compressed.
The Compression Algorithm Level specifies
how much the data is compressed. The combination of the two settings
determines the final file size.
The settings names are:
- Content Compression level for
PDF documents created by the report service
- Content Compression level for PDF documents created
by the batch report service
Valid choices for compression algorithm level are 0 (no compression)
to 9 (maximum compression). The default is 9.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
In the upper-left corner of the Scorecard pane,
click the arrow to view the Change view menu. Click Service,
and the service you want.
Click the arrow for the Actions menu next to the service
and click Set properties.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type the value
that you want for each of the PDF file settings.
Tip: If you want to reset a configuration setting to its
default value, select its check box and click Reset to
default value.
Click OK.
You can set the maximum execution time for the report
service, batch report service, and data movement service. If the
time limit is exceeded, the execution is canceled.
For example, you may want to limit execution time if you know
that there is something wrong if tasks take longer. You may also
want to ensure that no one task monopolizes server time to the detriment
of others.
The default is zero, which specifies no limit on execution time.
This setting has priority over the governor limit setting. See Set the Report Size Limit for the Report Data Service.
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
In the upper-left corner of the Scorecard pane,
click the arrow to view the Change view menu. Click Services and
the service you want.
Tip: You can also change the queue time limit settings
at the dispatcher or service level.
Click the arrow for the Actions menu next to the service
and click Set properties.
Tip: You can also set these service settings at the System level.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type a new value
for the Maximum execution time for the <service_name> (seconds) setting.
Click OK.
You can keep watch list report output for a specific
number of runs or for a specific number of days or months. For example,
you can keep up to 10 versions or you can keep the report output versions
for 2 days or 6 months.
There are two settings:
If you specify both settings, whichever is reached first determines
how many versions are kept.
The settings that you choose depend on how often watch list report
output is generated and your system resources. For example, if a
report runs nightly to provide output during the day on demand via
the portal and watch lists are updated on a weekly basis, you may
only want to keep four version each month, but no more than 5 versions
during that time. If a job is used to run reports and watch lists
are updated only when the job is run, you may only want to keep
1 version each day.
For more information on watch lists, see .
You must have the required permissions to access IBM
Cognos Administration functionality. See Secured Functions and Features.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
Click the arrow for the Actions menu next to System and
click Set properties.
Click the Settings tab.
Select Tuning from the Category list.
In the Value column, type a new value
for the Periodical document version retention age setting
and select Day(s) or Month(s) from
the drop-down menu.
In the Value column, type a new value
for the Periodical document version retention count setting.
Click OK.
A hotspot in a chart appears when you pause a pointer
over it. For example, a hotspot on a drill-down symbol or a tooltip
gives details about the column, line, or pie slice. The browser response
time increases with the number of hotspots. When charts with many
members are generated, the hotspots can become an additional burden
for the system resources, which can freeze the browser. To improve
performance, limit the number of hotspots that are generated for
Analysis Studio and Report Studio charts.
When you limit the number of hotspots, priority is given to items
such as axis labels and legend labels before individual graphical
elements such as bars, pie slices, and so on. Depending on the number
of items in a chart and the setting for maximum number of hotspots,
some axis items may have hotspots while other axis items and all
graphical elements do not, or all axis items and some graphical
elements may have hotspots while other graphical elements do not.
The maximum hotspot setting in Report Studio overrides this setting.
For more information, see the Report Studio Professional AuthoringUser Guide.
The default is an unlimited number of hotspots.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
Click the arrow for the Actions menu next to System and
click Set properties.
Tip: You can also change the hotspot setting at the dispatcher
or service level.
Click the Settings tab.
Select Tuning from the Category list.
Locate the Number of hotspots generated in a
chart by the Batch report service or the Number
of hotspots generated in a chart by the Report service setting.
In the Value column, click the arrow next to Unlimited and
then click <Number>. Type a new value for
the maximum number of hotspots
Click OK.
In IBM Cognos 8, you can choose to compress
email attachments above a specific size, or disable compression.
By default, compression is disabled. If you want email attachments compressed,
change the default behavior using the configuration setting, Maximum
size of an uncompressed email attachment in MB.
An email attachment must be at least 1MB to be compressed.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Configuration tab, click Dispatcher
and Services.
Click the dispatcher you want.
For DeliveryService, click the set
properties button.
Click the Settings tab.
To filter the settings, in the Category box,
click Tuning.
Specify a value for the Maximum size of an uncompressed
email attachment in MB setting. The following settings
that are available.
|
Disable compression | Type 0 (zero). This is the default
setting. |
Compress email attachments if the attachment
is greater than n. N is the size of the attachment
in MB. | Type n, where n is the size
of the attachment in MB. |
Click OK.
Click the Configuration link in the
path at the top of the page.
You return to the list of dispatchers.
If you have more than one dispatcher configured, perform
steps 4 to 10 for each remaining dispatcher.
Using IBM Cognos Configuration, stop and then restart IBM
Cognos 8.
For information about stopping IBM Cognos 8, see the Installation and Configuration Guide.
To limit the resources, such as memory, that are used
by Report data service, IBM Cognos 8 restricts the size
of the report data that can be sent out. If you receive errors in
IBM Cognos 8 Go! Office that a report result is
too large, you can increase the size limit for report data by changing
the Governor limit setting.
The maximum execution time setting has priority over this setting.
Start IBM Cognos Connection.
In the upper-right corner, click Launch, IBM
Cognos Administration.
On the Status tab, click System.
In the upper-left corner of the Scorecard pane,
click the arrow to view the Change view menu. Click Services,
and then click Report Data.
Click the arrow next to ReportDataService to
view the Actions menu, and then click Set properties.
Click the Settings tab.
In the Value column, change the number
for Governor limit (MB).
Click OK.
