Design and Implementation for Checkpointing of Distributed Resources Using Process-Level Virtualization

System-level checkpoint-restart is a critical technology for long-running jobs in high-performance computing. Yet, only two approaches to checkpointing MPI applications continue to survive in wide use today. One approach is to use the kernel module-based BLCR in combination with an MPI checkpoint-restart service particular to the MPI implementation in use. Unfortunately, this lacks support for some important Linux system services such as SysV IPC (e.g., shared memory objects). A second approach has been to use the original 2009 DMTCP implementation (herein referred to as DMTCP-09) for transparent, system-level checkpointing. Unfortunately, DMTCP-09 lacked support for checkpointing many of the necessary features found by MPI in a modern batch environment. These include: ssh, the InfiniBand network, process migration (restarting an MPI application on different cluster nodes), and modified file path prefixes on restart (typically due to a changing current directory, mount points, library paths, etc.). This work presents DMTCP-PV, a new user-space transparent checkpointing system based on the concept of process virtualization. This approach separately models the state of each local or distributed subsystem while decoupling it from the core checkpointing engine. By separating these concerns, a domain expert can extend checkpointing into a new domain without any knowledge of the core checkpointing engine. This allowed DMTCP-PV to address the deficiencies noted above and many others. It is shown that the runtime overhead of DMTCP-PV is generally less than 1%, and the checkpointing time is dominated by the time to write an image file to stable storage.