<p>Distributed transaction can include records of multiple class/clusters. The protocol used is an optimistic 2-phase commit, very similar to the one used in Google BigTable (<a href="https://arxiv.org/html/1106.3325" rel="nofollow noreferrer">https://arxiv.org/html/1106.3325</a>). The consensus is based on a <code>writeQuorum</code> that is majority by default, but can be relaxed (eventual consistency) or increased (=all) to have no dirty reads between servers.</p>
Does OrientDB support multi-cluster transactions?
<p>I'm trying to understand what sort of distributed transactions OrientDB supports. The documentation on distributed transactions here:</p>

<p><a href="http://orientdb.com/docs/last/Distributed-Architecture.html#distributed-transactions" rel="nofollow noreferrer">http://orientdb.com/docs/last/Distributed-Architecture.html#distributed-transactions</a></p>

<p>Seems to be describing transactionally updating replicas of a cluster using a consensus protocol, but does not describe anything about updating multiple clusters on multiple servers. </p>

<p>Are distributed transactions in OrientDB limited to executing on a single cluster, or can ACID transactions be executed on multiple clusters on multiple servers? If so, what is the mechanism that OrientDB uses to accomplish this? </p>