Abstract: This paper presents a new network mirroring approach for highly available Linux clusters based on replicating disk transactions at the kernel system calls level. The system is designed to allow reliable, and secure bi-directional mirroring over unreliable, slow, or insecure networks including Wide Area Networks (WANs) and dialup links without the need of any special hardware. The new approach can operate in different modes to optimize the  performance and bandwidth consumption on wide range of environments.