Write mem command on ACE

Question

Does ACE  , automatically save the running config to startup config  ,or I need save the config on the primary whenever I make changes  .
As till date  I thought that the config will be saved automatically ,until I ran into an issues.
Had setup my ACE in active standby .   Recently added couple vips on the primary  ,and dint do write mem.
for some reason primary went offline ,secondary took over ,but bcoz of preempt enabled ,when primary was back online   ,it tried taking over ,but there was a config mismatch .
And I see the both the LBs status as active /active.
Can any please clarify ,this as just bcoz of not running the write mem all  ,it happened that both my ACEs became active/active .
which created a problem in our lab environment

Answer 1

Active/active will happen only when there is a communication problem between the two ACE modules, other factors (like config mismatch, certificate mismatch) will not cause this. have you checked FT related logs at time of primary ACE reload.
regarding config mismatch case also, when primary ace boots up (if there is a proper communication between two ACE module) it will not immidiately become active, it will move form all stages of FT which include Bulk sync also, where in both module try to sync their configuration. Even if for some reason it fails, the situation will not result in Active/active.
only make sure that your FT config was present in your startup config at time of boot