/etc/conf/cf.d/mtune is a text file containing the minimum default and maximum settings for each tunable parameter. The maximum is the SCO recommended maximum, and can be exceeded for some parameters.
/etc/conf/cf.d/stune contains the settings that are different from the default that are in the current configuration.
Increasing values generally increases the size of the kernel, though memory isn't much of an issue these days. Increasing too much though may hurt performance by making searches through cache longer than re-retrieving data from disk for example.
Semaphores are used for program to program communication. How many you need will depend upon how your application software is written, and how many concurrent sessions there are.
As a general rule, you can start by doubling the value of any parameter that shows it is being exceeded.
My customer is worried from the warnings he is getting after he changed the values for some semaphores parameters and relinked the kernel .
the search is much faster now and more users can access the database , but he is afraid that his database will crash or fail due to the warnings he is getting from the kernel parameters .
Do you think these warning could lead to something serious or it is just a notes that values are exceeded?
If the only warnings come from the re-linking process and not from day to day operations, then there should be no concern.
You could always modify the mtune file so that the maximum value is greater than the value you have chosen, then the kernel would re-link with no warnings.