RRDtool vs Kiali: What are the differences?
RRDtool: High performance data logging and graphing system for time series data. RRDtool lets you log and analyze the data you gather from all kinds of data-sources (DS). The data analysis part of RRDtool is based on the ability to quickly generate graphical representations of the data values collected over a definable time period; Kiali: Service mesh observability and configuration. It is an observability console for Istio with service mesh configuration capabilities. It helps you to understand the structure of your service mesh by inferring the topology, and also provides the health of your mesh.
RRDtool and Kiali can be primarily classified as "Monitoring" tools.
RRDtool is an open source tool with 579 GitHub stars and 200 GitHub forks. Here's a link to RRDtool's open source repository on GitHub.