This is my point Marcelo, just "adding a processor" is not easy in the workstation world. Even if the PC's and Mac's out there have up to 4 or 8 CPU kernels, they are not easily available to the application programmer. And I can assure you that programming an application that makes deliberate use of a multi core CPU is one of the most difficult (error-prone) activities in the SW industry...
To repeat: In this example the simple solution will not receive any "risk control credits", but a complicated solution will. That is counter-productive for safety, in my opinion.
I do understand that. I only said about the separate processor IS a risk control option, but now one easily implemented one; and, also, not the needed one in general. But you have to know, and justify, why you do not need it.
Back to the example (and i had the ideia of using a practical application for this discussion):
The hazardous situation is that the X-ray images from the PACS are lost because the database server crashes or something similar.
The harm is that the patient may need to take new X-ray images and thus be exposed to more radiation. Not a big thing for my client's modality BTW, but it still is an identified hazard. For some other modalities the exposures may be higher
First of all, the "something similar" is a problematic statement here, because, regarding software, the sequence of events that led to the hazardous situation is extremely important (i´d say more than in the case of only hardware) because you need to know in what part of the sequence the software failure might contribute to the risk.
To illustrate this, please take a look at the attached file. Please keep in mind that it´s only a direct application of the ISO 14971 concepts to the situation you mentioned, not taking into consideration other factors.
In this case as illustrated (and it seems to illustrate the example you mentioned), i think we need more information because, as it´s written, we do not know the cause of the database crash. Please note that the probability P2 will probably be set to 1 (100 % chance) because, if the database images are lost, surely the harm will occur.
But P2 might happen due to a lot of factors...as written, the thing you need to do is to
What you might need to lower, then, is probability P1, but as written, i do not know what is the cause of the database failure (can be software, can be hardware - also, it´s interesting to not that even P2 is novery clear, because if we determine that in this hazardous situation the fault was of the hardware, then P2 would also be due to the hardware fault, and then the software would have played no role in the hazardous situation).
You would need, then, to identify a hazardous situation which would be caused by software, and then you might need software hazard control.