openUTM offers the two variants UTM-S and UTM-F for the operation of an application. These two variants can be characterized as follows.
UTM-S (UTM-Secure): a high level of security through universal restart functions
UTM-F (UTM-Fast): high performance with limited restart functions
UTM-S works with comprehensive transaction logging of all user and administration data. UTM-F, on the other hand, only executes transaction logging for administration data and therefore requires fewer I/Os. For this reason, UTM-F has better performance, but does not have complete restart capability. The two variants barely differ with respect to the administration data. Details can be found in the openUTM manual “Administering Applications” in the sections describing the corresponding administration calls.
You specify which variant a UTM application will use during generation of the UTM application.
The two variants function in the same manner during operation. UTM-F also executes transaction processing according to the “all or nothing” principle and guarantees the consistency of the data when used in conjunction with one database system.
Differences between the two variants only become apparent after the end of the application run (normal termination or an application crash):
In the case of standalone applications, for example, UTM-F does not save any user data for the following restart (application warm start). In UTM cluster applications, UTM-F does not save the user data until the user signs off.
The following sections describe in more detail how the two variants behave during a restart.