Applied Dimensionality

Cognos 8 BI Tuning Hard Drive Usage

Posted at — Aug 5, 2009
Cognos 8 BI Tuning Hard Drive Usage

Just a quick hint and a reminder: there is a configuration option forcing Cognos to store temporary report results in memory rather than dropping them on disk. It’s especially usefull for DMR’s they are frequently cached on disk.

Quote from Architecture and Deployment Guide.

Depending on the size of reports and the amount of available memory, IBM Cognos 8 may access a physical disk when processing reports. To improve performance, you can ensure that report processing uses available memory rather than disk space. Using memory instead of disk space is particularly beneficial in cases where temporary files are created on IBM Cognos 8 servers, causing information transfer from memory to disk. You can monitor the occurrence of temporary files using the c8_location\temp directory.Monitor this folder during report processing periods to determine whether temporary files are created as cclvpage*.tmp.

To ensure that IBM Cognos 8 uses memory instead of disk space, in the rsvpproperties.xml file, edit the VirtualMemoryDiagnostics property to use unlimited memory (value = 2) rather than limited memory (value = 0): <property>VirtualMemoryDiagnostics</property><br /> <value type="long">2</value> Note: Remove the comment to enable the VirtualMemoryDiagnostics property. For information about using the rsvpproperties.xml file, see “Advanced Report Processing Configuration Settings” (p. 96).

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