User Area > Advice
Typical warning message found in the LUSAS Solver text output
(*.out) file:
***WARNING*** SYSTEM PARAMETER
LFRADD= 5000 TOO LOW - DISK FILES MAY GROW LARGER THAN NECESSARY
INCREASING LFRADD MAY REDUCE SIZE OF DISK FILES
Most common causes & links to solutions
This warning message is not normally a cause for concern unless it is the only warning message which occurs before the end of the OUT
file in a failed Solver run.
The remedy is to increase the Solver system parameter
LFRADD to 15000 (default value is 5000)
as a first step to ensure sufficient storage for all the free memory locations. This can be
set prior to solving a model in the Modeller user interface via:
File > Model Properties... >
Solver System Variables tab
The parameter may be incremented in steps of 5000
until the warning
is eliminated. If the analysis completes successfully, there is no need to
change this parameter. The results will be unaffected. The reason to
change this parameter will be when the analysis uses all the available
disk space, fails AND this message is found in the output file.
More on cause & theory links
The system parameter "LFRADD" controls the size of the free disk space administrator array. That is, it contains details of all the areas of free virtual memory space in each of the LUSAS Solver scratch
(temporary) files.
In looking at the temporary
file sizes, it is sometimes found that the problem (.prb) file increases significantly in size as the solution progresses. This file
should grow during the first "element assembly" and "stress recovery"
phases but remain constant thereafter and the reason for its further growth is due to fragmentation of the scratch file. For very large dynamic or nonlinear analyses (i.e. where the assembly and recovery stages are processed a large number of times) the default value for the LFRADD system parameter can mean that smaller available memory locations are not stored to make space for larger, and more dominant memory space storage - these smaller areas of memory are responsible for this fragmentation.
More on how LUSAS uses PC
resources
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