Technically speaking, it should work, however it is no longer available during partitions since the only 2 nodes partition creates two minority partitions, so t

Technically speaking, it should work, however it is no longer available during partitions since the only 2 nodes partition creates two minority partitions, so the algorithm can't promote a new leader, nor make progresses since new log entries can't reach the majority. Basically you have the same properties using a single node without consensus, if not for the data redundancy. However it is not something like: one node dies, the other can continue. TLDR: 3 nodes is the practical minimum.