NDB Cluster Internals  /  NDB Kernel Blocks  /  The CMVMI Block

4.2 The CMVMI Block

This block is responsible for configuration management between the kernel blocks and the NDB virtual machine, as well as the cluster job que and cluster transporters. It is found in storage/ndb/src/kernel/blocks/cmvmi, and contains these files:

  • Cmvmi.cpp: Implements communication and reporting methods for the Cmvmi class.

  • Cmvmi.hpp: Defines the Cmvmi class.

During startup, this block allocates and touches most of the memory needed for buffers used by the NDB kernel, such as those defined by IndexMemory, DataMemory, and DiskPageBufferMemory. At that time, CMVMI also gets the starting order of the nodes, and performs a number of functions whereby software modules can affect the runtime environment.