How is BLCR different than “user-level” checkpointing libraries like Condor, etc.?
BLCR performs checkpointing and restarting inside the linux kernel. While this makes it less portable than solutions that use user-level libraries, it also means that it has full access to all kernel resources, and can thus restore resources (like process IDs) that user-level libraries cannot. This also allows BLCR to checkpoint/restart groups of processes (such as shell scripts and their subprocesses), together with the pipes that connect them.
