While FoundationDB uses Paxos for cluster state (like leader election), it is not on the commit path for a transaction. If any process fails in the transaction system (not storage processes), the cluster is reconfigured by the coordinators and every component is replaced. Transactions do not proceed during failures, but the cluster will replace the failed process in a few seconds and resume.

(This is not meant to be a contradiction, just pointing out an important difference compared to systems that allow progress in parallel with failures.)