VM clock synchronization measurements

Abstract

Abstract-A modern twist to clock synchronization is the push towards server virtualization and cloud computing. Distributed applications now often run on geographically-distributed, virtualized servers that are isolated from the underlying hardware. Despite the fact that most applications run well in an abstracted environment without direct hardware access, tight real-time synchronized clocks are still necessary.We performed a set of experiments to quantify the additional clock error when running the NTP daemon inside a Virtual Machine. We found that the delay asymmetry is relatively small when running in a non-virtualized environment, but quite significant in a virtualized environment.

Timing errors and temporal uncertainty in clinical databases—A narrative review

“…Computer clocks are generally well-synchronized and have relatively low drift rates, rendering them suitable as a source of truth in many situations ( 190 , 191 ). However, care must be taken when using clocks on virtual servers since their drift rates may be higher than hardware based clocks ( 192 – 194 ). While smartphones and wristwatches are ubiquitous and relatively accurate sources of time ( 195 ) they can also act as a source of infection, so their use for timing purposes may be discouraged in some clinical situations ( 196 – 198 ).…”