How and where does a corda node (Y1) leave a message for a backup node (Y2) so that Y2 can resume the flow that got interrupted because Y1 went down?

Question

When in a hot-cold corda deployment where say the nodes are: c1 (PartyA), c11 (PartyA backup), c2 (PartyB) Now if a flow has been initiated by c2 and c1 is responding but it