FMEA (Failure Modes and Effects Analysis)

Persistency FMEA		status: valid security: NO safety: ASIL_B
tags: persistency realizes: wp__feature_fmea
doc__persistency_fmea		Generic Document

The FMEA for the feature Persistency is performed. To show evidence that all failure initiators are considered, the applicability has to be filled out in the following tables. For all applicable failure initiators, the FMEA has to be performed.

Failure Mode List

Fault Models for sequence diagrams

Table 16 Fault Models for sequence diagrams :header-rows: 1 :widths: 10,20,10,20

ID	Failure Mode	Applicability	Rationale
MF_01_01	message is not received (is a subset/more precise description of MF_01_05)	yes	Persistency (feat_saf_fmea__persistency__message_nreived)
MF_01_02	message received too late (only relevant if delay is a realistic fault)	yes	Persistency (feat_saf_fmea__persistency__late_message)
MF_01_03	message received too early (usually not a problem)	no	Failure initiator not applicable at persistency, so no mitigation is needed.
MF_01_04	message not received correctly by all recipients (different messages or messages partly lost). Only relevant if the same message goes to multiple recipients.	no	Failure initiator not applicable at persistency, so no mitigation is needed.
MF_01_05	message is corrupted	yes	Persistency (feat_saf_fmea__persistency__corrupted_message)
MF_01_06	message is not sent	yes	Persistency (feat_saf_fmea__persistency__not_sent)
MF_01_07	message is unintended sent	no	Failure initiator not applicable at persistency. Feature developed fully deterministic, so no unintended messages are expected.
CO_01_01	minimum constraint boundary is violated	no	Failure initiator not applicable at persistency, so no mitigation is needed.
CO_01_02	maximum constraint boundary is violated	no	Failure initiator not applicable at persistency, so no mitigation is needed.
EX_01_01	Process calculates wrong result(s) (is a subset/more precise description of MF_01_05 or MF_01_04). This failure mode is related to the analysis if e.g. internal safety mechanisms are required (level 2 function, plausibility check of the output, …) because of the size / complexity of the feature.	no	Failure initiator not applicable at persistency, so no mitigation is needed. The feature is developed fully deterministic, so no wrong results are expected caused by persistency
EX_01_02	processing too slow (only relevant if timing is considered)	no	Failure initiator not applicable at persistency. The feature is developed fully deterministic, so no processing too slow is expected caused by persistency.
EX_01_03	processing too fast (only relevant if timing is considered)	no	Failure initiator not applicable at persistency, so no mitigation is needed. The feature is developed fully deterministic, so no processing too fast is expected caused by persistency.
EX_01_04	loss of execution	yes	Persistency (feat_saf_fmea__persistency__err_handl)
EX_01_05	processing changes to arbitrary process	no	Failure initiator not applicable at persistency, so no mitigation is needed.
EX_01_06	processing is not complete (infinite loop)	no	Failure initiator not applicable at persistency, so no mitigation is needed. The feature is developed fully deterministic, so no infinite loop is expected caused by persistency.

FMEA

For all identified applicable failure initiators, the FMEA is performed in the following section.

Persistency		status: valid
failure_effect: Message is not received so the feature persistency is not available. fault_id: MF_01_01 sufficient: yes mitigated_by: aou_req__persistency__error_handling violates: feat_arc_dyn__persistency__check_key_default, feat_arc_dyn__persistency__delete_key, feat_arc_dyn__persistency__flush, feat_arc_dyn__persistency__read_key, feat_arc_dyn__persistency__read_from_storage, feat_arc_dyn__persistency__write_key, feat_arc_dyn__persistency__snapshot_restore
User is not able to use the feature. Middleware cant be used. User is not able to use the feature. Middleware cant be used. Loss of execution can only be caused by the application, not by the persistency feature itself. Failure handling is addressed to the application by the aou_req__persistency__error_handling.
feat_saf_fmea__persistency__message_nreived		Feature FMEA (Failure Mode and Effects Analysis)

Persistency		status: valid
failure_effect: message received too late. fault_id: MF_01_02 sufficient: yes mitigated_by: aou_req__persistency__error_handling violates: feat_arc_dyn__persistency__check_key_default, feat_arc_dyn__persistency__delete_key, feat_arc_dyn__persistency__flush, feat_arc_dyn__persistency__read_key, feat_arc_dyn__persistency__read_from_storage, feat_arc_dyn__persistency__write_key, feat_arc_dyn__persistency__snapshot_restore
Subset of MF_01_01 if the delay is to long.
feat_saf_fmea__persistency__late_message		Feature FMEA (Failure Mode and Effects Analysis)

Persistency		status: valid
failure_effect: message is corrupted so the feature persistency is not available. fault_id: MF_01_05 sufficient: yes mitigated_by: aou_req__persistency__error_handling violates: feat_arc_dyn__persistency__check_key_default, feat_arc_dyn__persistency__delete_key, feat_arc_dyn__persistency__flush, feat_arc_dyn__persistency__read_key, feat_arc_dyn__persistency__read_from_storage, feat_arc_dyn__persistency__write_key, feat_arc_dyn__persistency__snapshot_restore
Covered by MF_01_01
feat_saf_fmea__persistency__corrupted_message		Feature FMEA (Failure Mode and Effects Analysis)

Persistency		status: valid
failure_effect: message is not sent so the feature persistency is not available. fault_id: MF_01_06 sufficient: yes mitigated_by: aou_req__persistency__error_handling violates: feat_arc_dyn__persistency__check_key_default, feat_arc_dyn__persistency__delete_key, feat_arc_dyn__persistency__flush, feat_arc_dyn__persistency__read_key, feat_arc_dyn__persistency__read_from_storage, feat_arc_dyn__persistency__write_key, feat_arc_dyn__persistency__snapshot_restore
Covered by MF_01_01 because the violation cause is the same.
feat_saf_fmea__persistency__not_sent		Feature FMEA (Failure Mode and Effects Analysis)

Persistency		status: valid
failure_effect: loss of execution will lead to an unavailability of the persistency feature. fault_id: EX_01_04 sufficient: yes mitigated_by: aou_req__persistency__error_handling violates: feat_arc_dyn__persistency__check_key_default, feat_arc_dyn__persistency__delete_key, feat_arc_dyn__persistency__flush, feat_arc_dyn__persistency__read_key, feat_arc_dyn__persistency__read_from_storage, feat_arc_dyn__persistency__write_key, feat_arc_dyn__persistency__snapshot_restore
User is not able to use the feature. Middleware cant be used. Loss of execution can only be caused by the application, not by the persistency feature itself. Failure handling is addressed to the application by the aou_req__persistency__error_handling.
feat_saf_fmea__persistency__err_handl		Feature FMEA (Failure Mode and Effects Analysis)