XenLR: Xen-based Logging for Deterministic Replay

Virtual machine (VM) based logging-and-replay technology has attracted much attention for system security, fault tolerance, and debugging. However, so far there is not a replay system designed on virtual machine monitor Xen. In this paper, XenLR presents the design and implementation of a logging tool for full system replay on Xen. To reduce the design complexity, XenLR is achieved on a lightweight VM mini OS. Our preliminary work dedicates to identify architectural non-deterministic events and record them compactly. XenLR does not modify the guest OS and only need to record the external inputs (keyboard input and time update on mini OS). The log data are saved in the privileged domain¿s file system through transmission channels. The experiments indicate that XenLR results in low time and space overhead. Overhead due to logging is imperceptible for interactive use. The log files grow at 1.4 MByte/day, so it causes litter space consumption for today¿s large capacity disk storage.