Transaction not found in one of the high-availability multiple nodes setup

[shun0309-zz]

I am running two nodes of bitcore-node with insight API. When I query a transaction on both nodes using the API, one of them returning "not found" while the other one returns the info about the transaction without any error. The transaction indeed has "confirmations: 0".

After tracing the code from insight API to bitcore-node, the reason of the API returning "not found" is the db doesn't contain the transaction record at all.

May I ask

1. What is the expected behaviour when the bitcore-node encounters some unconfirmed or possibly orphaned transactions?
2. How could it be possibly ended up into the situation of one node contains the record but the other doesn't? Given that the transaction was received two months ago.
3. If one of the node fails somehow hence resulting in corrupted database records, how can I fix or reset the node? downloading the whole blockchain again?

Thanks.

[shun0309-zz]

To clarify, the nodes start at the same time. They synchronise at roughly the same time across their history.