Software Failure Modes Effects Analysis (SFMEA)

A software FMEA determines the software failure modes that are likely to cause failure events.   Then it determines what single or multiple point failures could produce these top level events. Software FMEAs useful when designing or testing the error handling part of your software.   Software FMEAs are also needed in order to develop inspection criteria for requirements, design, and code that are geared towards the appropriate failure modes.  Design reviews are more effective when you know in advance the types of failure modes that are most likely.  The below illustrates the software FMEA process.

Below is a matrix showing the categories of product and process failure modes.  The number shown in each of the below column indicates how many unique failure modes of this type apply to this type of FMEA.  You can see that more than 300 software failure modes will be discussed in class.

Common mistakes made when doing software FMEAs include:

• Attempting to perform them on 100% of the design or code instead of sampling the design/code most likely to cause a serious failure
• Neglecting to use standard checklists for software failure modes
• Forgetting the software does not have an on site "replace" maintenance mode, only onsite reload, restart and workaround

• Excluding hardware from the analysis or isolating the software from the rest of the system
• Starting with "software fails" as the failure mode

• Not having the appropriate subject matter experts in the analyses
• Neglecting to prune the results for low severity and low probability
• Neglecting to add the "shall nots" divulged from the FMEAs into the appropriate design documents and test plans
• Neglecting to review past historical failure modes

Products and Services related to software FMEAs