automatic switching between cpua and cpub

[DjeSan]

hello
I have a problem with my 4400 R10.1 that automatically switches to the cpub when it should be in STAND-BY and the cpua in MAIN, the 4400 restarts alone and the switch command is applied automatically. After reading the documentation I understand that it could be :
-a loss of clock (this is not the case)
- A bad disk sector ( I checked with the smartctl -a /dev/hda command but I don't know how to interpret the results )
- switch command requested by the system ( I never activated this )
-panel on the master CPU card
-IO2N board failure ( but how to check this please ??? a command ???? )
currently with TWIN command all is good I'm afraid it will reboot again

[oldboy]

So the big question is why does it matter which cpu is main?? they should never many years ago named them A and B as long as the DB is in sync and netadmin is correct the system would run fine on either.,

A incvisu -B 1 on the now stand-by should give you a clue to why it switched