An improvement introduced in MySQL NDB Cluster 7.2.7 saves memory used by buffers for communications between threads. One way in which this was implemented was by not allocating buffers between threads which were assumed not to communicate, including communication between local query handler (LQH or LDM) threads.

However, the BACKUP kernel block is used by the LDM thread, and during NDB native backup the first instance of this block used by the first LDM thread acts as a client coordinator, and thus attempts to communicate with other LDM threads. This caused the START BACKUP command to fail when using ndbmtd configured with multiple LDM threads.

The fix for this issue restores the buffer used for communication between LDM threads in such cases. (Bug #14489398)

When reloading the redo log during a node or system restart, and with NoOfFragmentLogFiles greater than or equal to 42, it was possible for metadata to be read for the wrong file (or files). Thus, the node or nodes involved could try to reload the wrong set of data. (Bug #14389746)

When an NDB table was created during a data node restart, the operation was rolled back in the NDB engine, but not on the SQL node where it was executed. This was due to the table .FRM files not being cleaned up following the operation that was rolled back by NDB. Now in such cases these files are removed. (Bug #13824846)