Method and computer system for making a computer have high availability

A computer system having high availability, comprising:

• a host computer with a host virtual machine container;
• a servant computer with a servant virtual machine container;
• a host virtual machine running on said host virtual machine container;
• a servant virtual machine running on said servant virtual machine container;
• a communication channel operatively connecting said host computer and said servant computer;
• said communication channel being configured to use an I/O instruction as a transaction boundary to trigger synchronization between said host virtual machine and said servant virtual machine;
• an instruction queue;
• a main memory;
• a journal memory;
• and
• wherein the host virtual machine is configured to load instructions from the main memory into its instruction queue, execute the instructions in the instruction queue and write the data into the main memory, and save the instructions into a journal memory of the host virtual machine in the form of journal storage instructions.

A computer comprising a virtual machine container and a virtual machine running on said virtual machine container, wherein said virtual machine comprises:

• an instruction queue;
• a main memory;
• a journal memory;
• and
• wherein the virtual machine is configured to load instructions from the main memory into its instruction queue, execute the instructions in the instruction queue and write the data into the main memory, and write the instructions in the form of journal storage instruction into a journal memory of the virtual machine;
• and
• wherein said virtual machine is further configured to use an I/O instruction as a transaction boundary to trigger a synchronization operation with a virtual machine of an other computer.