1. A method, comprising: preloading interceptors for fork( ) and execO for one or more applications in an application group; preloading interceptors for file operations for the one or more applications in the application group; creating at least one full checkpoint for the one or more applications in the application group; creating at least one incremental checkpoint for the one or more applications in the application group; merging the at least one incremental application checkpoint against the at least one full application checkpoint; synchronizing checkpointing across all applications in the application group; and taking a storage checkpoint for at least one of the at least one full checkpoint and the at least one incremental checkpoint; wherein the one or more applications are comprised of one or more processes, and each process comprised of one or more threads; wherein intercepted file operations are added to a file operations data structure upon entering said file operations interceptors, intercepted file operations are removed from said file operations data structure upon completion of said file operations, and checkpointing is disabled between adding said intercepted file operations to said file operations data structure and a start of execution of said file operations; and wherein checkpointing of user-space pages is comprised of write-protecting one or more user-space memory pages, detecting an attempt to write to said one or more user-space memory pages, and including said one or more user-space memory pages in a checkpoint.