Administering Platform LSF - SAS

Approaches to Checkpointing
Kernel-level checkpointing
User-level checkpointing
Chapter 23
Job Checkpoint, Restart, and Migration
LSF provides support for most checkpoint and restart implementations through
uniform interfaces, echkpnt and erestart. All interaction between LSF and
the checkpoint implementations are handled by these commands. See the
echkpnt(8) and erestart(8) man pages for more information.
Checkpoint and restart implementations are categorized based on the facility
that performs the checkpoint and the amount of knowledge an executable has
of the checkpoint. Commonly, checkpoint and restart implementations are
grouped as kernel-level, user-level, and application-level.
Kernel-level checkpointing is provided by the operating system and can be
applied to arbitrary jobs running on the system. This approach is transparent
to the application, there are no source code changes and no need to re-link
your application with checkpoint libraries.
To support kernel-level checkpoint and restart, LSF provides an echkpnt and
erestart executable that invokes OS specific system calls.
Kernel-level checkpointing is currently supported on:
◆ Cray UNICOS
◆ IRIX 6.4 and later
◆ NEC SX-4 and SX-5
See the chkpnt(1) man page on Cray systems and the cpr(1) man page on
IRIX systems for the limitations of their checkpoint implementations.
LSF provides a method to checkpoint jobs on systems that do not support
kernel-level checkpointing called user-level checkpointing. To implement
user-level checkpointing, you must have access to your applications object files
(.o files), and they must be re-linked with a set of libraries provided by LSF in
LSF_LIBDIR. This approach is transparent to your application, its code does not
have to be changed and the application does not know that a checkpoint and
restart has occurred.
Application-level checkpointing
The application-level approach applies to those applications which are
specially written to accommodate the checkpoint and restart. The application
writer must also provide an echkpnt and erestart to interface with LSF. For
more details see the echkpnt(8) and erestart(8) man pages. The
application checkpoints itself either periodically or in response to signals sent
by other processes. When restarted, the application itself must look for the
checkpoint files and restore its state.
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