What is creating these Vmm files?
Can the size be controlled?
Can they be removed or deleted
File system almost full to vmm* file in the temp folder
Vmm files are virtual memory tables created when running reports with large data sets.
vmm files are functionally similar to Windows virtual memory page files.
In earlier versions of Cognos we had to enable advanced parameters to utilize the virtual memory features.
In the newer versions of Cognos we have incorporated that functionality into the report server by default.
These files (the VMM temp files) are being created when the you are running large
reports in external formats.
vmm files are expected in the temp directory.
Can the size be controlled? Unfortunately no.
You can shrink the size of your reports and the datasets being pulled back that would be it.
You can try looking at the time the files are created to see what reports are started at that time in order to see what reports could create the files.
For the question regarding removing these temp files :
Yes, you can remove these files as long as they are not being used by a report currently running.
if you remove them while the report is running that would cause the report to fail.
They are also deleted on a restart of the dispatcher.
As per the description of the 'Temporary files location' parameter in Cognos Configuration - Environment, The product creates temporary files each time you open a report.
The product stores these temporary files in the location you specify.
The product may not delete all temporary files when it closes and they may remain on your computer until you delete them.
Recommendation is to ensure that there is enough disk space in the temp area.
You could change the temporary files location in Cognos Configuration to point to a location outside the Cognos installation.
Sometimes, creation of these files is associated with crashes of BiBusTKserverMain processes that are spawn by a Cognos dispatcher to execute reports.
If this would be the case, there would be core files in bin directory of dispatcher installations with the same timestamp as the Vmm file.