havaclk

Havaclk is a term used in information technology to describe mechanisms for maintaining accurate time across distributed systems with an emphasis on high availability. In practice, havaclk covers hardware and software approaches that provide redundant time sources, robust failover, and precise synchronization to minimize clock skew and drift.

The name appears as a portmanteau of "high availability" and "clock" in various online discussions and project READMEs. There is no single standardized definition, and usage varies by vendor and community.

Havaclk-enabled systems typically combine multiple time sources (for example GPS or GNSS receivers, network time protocols, and local oscillators), with monitoring and automatic switchover. They rely on synchronization protocols such as NTP, PTP (IEEE 1588), or custom consensus schemes, and aim to provide monotonic time even in the event of source failure. They may employ hardware timestamping, kernel-space timekeeping, and dedicated time servers.

Common patterns include primary-secondary time servers with automated failover, hierarchical time forests, and edge devices with local oscillators and secure time distribution. Observability tools track offset, jitter, and stratum levels to ensure confidence in time quality.

Use cases include data centers, trading platforms, and avionics test environments where time integrity is critical. Limitations include complexity, potential single points of failure if misconfigured, and dependence on external time sources or satellite signals subject to outages.