Allocating Sufficient Space For The Temporary Files; Optimization Of The Operating Environment - IBM Cognos User Manual

You may also want to configure the build server to use striping (RAID level 0)
rather than mirroring, assuming that you have a backup for use if the system
crashes during a production build. The build time is reduced because data is
distributed among nonredundant disk drives.

Allocating Sufficient Space for the Temporary Files

You need different amounts of space for the temporary files during each cube
build phase.
v During the Data Read phase, the source data is read into a temporary work file
based on the model structure. Insufficient disk space and database connectivity
can cause problems at this stage.
v During the Metadata Update phase, the contents of the temporary work file are
compared to the categories in the model, to see which ones go into the cube,
and a copy of the file is created. The original work file is only deleted after
processing is complete and eligible categories are inserted into the cube.
Insufficient disk space and lack of memory can cause problems at this stage.
v During the Data Update phase, before the data points in the temporary work
file can be inserted into the partitioned cube, the data must be sorted and
consolidated. This requires several passes through the temporary file. The most
common issue during this phase is low system memory.
There is a formula you can use to estimate the amount of space to allocate for the
temporary files. If {([(A*4)+(B*4)+(C*16)+8]*D)/1024/1024}*2 is greater than 1431,
the space calculation is that number plus E. If the calculated result is less than or
equal to 1431, the required space is that number (do not add E).
Taking the test model as an example, the calculated space requirement is 7047 MB,
given the following input values:
v A = the total number of dimensions
v B = the number of dimension views associated with the PowerCube
v C = the number of regular measures (calculated measures are not counted)
v D = the number of input records for all transactional data sources
v E = 1431; the WorkFileMaxSize setting divided by 1024 * 1024 (MB)
To this number, you must add sufficient space for the PowerCube and the model
checkpoint files: 7 GB + 20% for the former, and a number equal to the model
working space for the latter.
We recommend that you point the Sort directory to the same location as the Data
Temporary File, with all other Cognos Transformer directory locations pointing to
another drive. You should then use a system performance monitor, during the cube
build, to check the amount of available disk space in the three cube build phases.

Optimization of the Operating Environment

You can adjust various settings, whether operating in UNIX, Linux, or Windows
environments, to shorten your cube build times.
Tip: When specifying the preference settings in the installation_location/
configuration/cogtr.xml file, use the installation_location/configuration/
cogtr.xml.sample file as a reference.
Optimize your system by changing the following default settings:
v WriteCacheSize
Chapter 9. Guidelines for Optimizing Production Environments
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