Open rte mca snapshot coordination (snapc) framework: overview of open rte's snapc framework, and selected modules. open mpi 1.6.5
Open RTE can coordinate the generation of a global snapshot of a parallel job from many distributed local snapshots. The components in this framework determine how to: Initiate the checkpoint of the parallel application, gather together the many distributed local snapshots, and provide the user with a global snapshot handle reference that can be used to restart the parallel application.
In order for a process to use the Open RTE SnapC components it must adhear to a few programmatic requirements.
First, the program must call ORTE_INIT early in its execution. This should only be called once, and it is not possible to checkpoint the process without it first having called this function.
The program must call ORTE_FINALIZE before termination.
A user may initiate a checkpoint of a parallel application by using the orte-checkpoint(1) and orte-restart(1) commands.
Open RTE ships with one SnapC component: full.
The following MCA parameters apply to all components:
snapc_base_verbose
Set the verbosity level for all components. Default is 0, or silent except on error.
snapc_base_global_snapshot_dir
The directory to store the checkpoint snapshots. Default is /tmp.
The full component gathers together the local snapshots to the disk local to the Head Node Process (HNP) before completing the checkpoint of the process. This component does not currently support replicated HNPs, or timer based gathering of local snapshot data. This is a 3-tiered hierarchy of coordinators.
The full component has the following MCA parameters:
snapc_full_priority
The component's priority to use when selecting the most appropriate component for a run.
snapc_full_verbose
Set the verbosity level for this component. Default is 0, or silent except on error.
The none component simply selects no SnapC component. All of the SnapC function calls return immediately with ORTE_SUCCESS.
This component is the last component to be selected by default. This means that if another component is available, and the none component was not explicity requested then ORTE will attempt to activate all of the available components before falling back to this component.