Selecting a Primary-Secondary Host Pair for Mirroring Virtual Machines

A computer implemented method of mirroring contents of a primary host computer system onto a secondary host computer system, the method comprising:

• tracking changes for each of a plurality of memory pages for one or more primary host virtual machines;
• tracking changes to a plurality of processor states for one or more primary host virtual machines;
• responsive to an occurrence of a checkpoint, stopping one or more of the primary host virtual machines;
• determining for the memory pages, if at least one particular memory page of the plurality of memory pages is a frequently changed memory page;
• in response to at least one particular memory page being a frequently changed memory page, marking the frequently changed memory page as writeable and copying the frequently changed memory page to a buffer;
• in response to a memory page being infrequently changed, marking the infrequently changed memory page as read only;
• resuming the one or more primary host virtual machines;
• and
• transmitting a copy of the memory pages, the buffer, and the changes to the processor states to the secondary host.