MySQL NDB Cluster 7.5 Release Notes
A node was permitted during a restart to participate in a backup before it had completed recovery, instead of being made to wait until its recovery was finished. (Bug #32381165)
        Running out of disk space while performing an
        NDB backup could lead to an unplanned
        shutdown of the cluster.
       (Bug #32367250)
        The default number of partitions per node (shown in
        ndb_desc output as
        PartitionCount) is calculated using the
        lowest number of LDM threads employed by any single live node,
        and was done only once, even after data nodes left or joined the
        cluster, possibly with a new configuration changing the LDM
        thread count and thus the default partition count. Now in such
        cases, we make sure the default number of partitions per node is
        recalculated whenever data nodes join or leave the cluster.
       (Bug #32183985)
        Event buffer congestion could lead to unplanned shutdown of SQL
        nodes which were performing binary logging. We fix this by
        updating the binary logging handler to use
        Ndb::pollEvents2() (rather than
        the deprecated pollEvents()
        method) to catch and handle such errors properly, instead.
       (Bug #31926584)
        Generation of internal statistics relating to
        NDB object counts was found to lead to an
        increase in transaction latency at very high rates of
        transactions per second, brought about by returning an excessive
        number of freed NDB objects.
       (Bug #31790329)