Incremental Checkpoints Research Articles

Survive: Pointer-Based In-DRAM Incremental Checkpointing for Low-Cost Data Persistence and Rollback-Recovery

This paper introduces the Survive DRAM architecture for effective in-memory micro-checkpointing. Survive implements low-cost incremental checkpointing, enabling fast rollback that can be used in various architectural techniques such as speculation, approximation, or low voltage operation. Survive also provides crash consistency when used as the frontend of a hybrid DRAM-NVM memory system. This is accomplished by carefully copying the incremental checkpoints generated in the DRAM frontend to the NVM backend. Simulations show that Survive only imposes an average 3.5 percent execution time overhead over an unmodified DRAM main-memory system with no checkpointing, while reducing the number of NVM writes by 89 percent over an NVM-only main-memory system.

VM-μCheckpoint: Design, Modeling, and Assessment of Lightweight In-Memory VM Checkpointing

Checkpointing and rollback techniques enhance reliability and availability of virtual machines and their hosted IT services. This paper proposes VM-μCheckpoint, a light-weight pure-software mechanism for high-frequency checkpointing and rapid recovery for VMs. Compared with existing techniques of VM checkpointing, VM-μCheckpoint tries to minimize checkpoint overhead and speed up recovery by means of copy-on-write, dirty-page prediction and in-place recovery, as well as saving incremental checkpoints in volatile memory. Moreover, VM-μCheckpoint deals with the issue that latency in error detection potentially results in corrupted checkpoints, particularly when checkpointing frequency is high. We also constructed Markov models to study the availability improvements provided by VM-μCheckpoint (from 99 to 99.98 percent on reasonably reliable hypervisors). We designed and implemented VM-μCheckpoint in the Xen VMM. The evaluation results demonstrate that VM-μCheckpoint incurs an average of 6.3 percent overhead (in terms of program execution time) for 50 ms checkpoint intervals when executing the SPEC CINT 2006 benchmark. Error injection experiments demonstrate that VM-μCheckpoint, combined with error detection techniques in RMK, provides high coverage of recovery.

INCREMENTAL CHECKPOINT SCHEMES FOR WEIBULL FAILURE DISTRIBUTION

Incremental checkpoint mechanism was introduced to reduce high checkpoint overhead of regular (full) checkpointing, especially in high-performance computing systems. To gain an extra advantage from the incremental checkpoint technique, we propose an optimal checkpoint frequency function that globally minimizes the expected wasted time of the incremental checkpoint mechanism. Also, the re-computing time coefficient used to approximate the re-computing time is derived. Moreover, to reduce the complexity in the recovery state, full checkpoints are performed from time to time. In this paper we present an approach to evaluate the appropriate constant number of incremental checkpoints between two consecutive full checkpoints. Although the number of incremental checkpoints is constant, the checkpoint interval derived from the proposed model varies depending on the failure rate of the system. The checkpoint time is illustrated in the case of a Weibull distribution and can be easily simplified to the exponential case.

High Performance Computing Systems with Various Checkpointing Schemes

Finding the failure rate of a system is a crucial step in high performance computing systems analysis. To deal with this problem, a fault tolerant mechanism, called checkpoint/ restart technique, was introduced. However, there are additional costs to perform this mechanism. Thus, we propose two models for different schemes (full and incremental checkpoint schemes). The models which are based on the reliability of the system are used to determine the checkpoint placements. Both proposed models consider a balance of between checkpoint overhead and the re-computing time. Due to the extra costs from each incremental checkpoint during the recovery period, a method to find the number of incremental checkpoints between two consecutive full checkpoints is given. Our simulation suggests that in most cases our incremental checkpoint model can reduce the waste time more than it is reduced by the full checkpoint model. The waste times produced by both models are in the range of 2% to 28% of the application completion time depending on the checkpoint overheads.

A Roll-Forward Recovery Scheme for Solving the Problem of Coasting Forward for Distributed Systems

In this paper, a new index-based hybrid checkpointing scheme has been proposed to tackle the problem arising due to "coasting forward". This scheme uses both incremental and communication-induced checkpoints. Failures have been classified as hard and soft in order to take the advantage (i.e. possible reduction of rollback) which the incremental checkpoints offer, while designing the recovery approaches for these two types of failures. The presented theoretical results show that for soft failures, the recovery approach offers maximum roll-forward.