\begin{table} \resizebox{\columnwidth}{!}{ \begin{tabular}{lm{0.2\linewidth}m{0.25\linewidth}m{0.3\linewidth}l} \toprule Project & Simulation Technique & Focus & Stakeholders & Modelling Capability \\ \midrule ExaDigiT~\cite{DBLP:conf/sc/BrewerMKWBHSGGW24} & CFD/HT, AI/ML & Energy Loss\newline Prediction,\newline {Heat Modelling} & HPC Engineers and Operators & {3D\textsuperscript{$\star$}}, {CH\textsuperscript{$\ddagger$}}, VP\textsuperscript{$\star$}, PE\textsuperscript{$\ddagger$}, RA, SE\textsuperscript{$\dagger$} \\ \midrule SmartDC~\cite{DBLP:conf/noms/ZhangZLZWC22} & CFD/HT, BIM, AI/ML & {Heat Modelling},\newline PUE optimization & Cloud Datacenter Engineers & {CH\textsuperscript{$\dagger$}}, PE, {3D\textsuperscript{$\star$}} \\ \midrule DyTwin~\cite{DBLP:conf/sc/TaheriBPRHDEWPM24} & Gaussian Process Regression, AI/ML & Anomaly Detection & Cloud Datacenter Operators & A\textsuperscript{$\star$}, FD, VP\textsuperscript{$\star$}, SE\textsuperscript{$\dagger$} \\ \midrule ChatTwin~\cite{DBLP:conf/sensys/LiW0Z0T23} & \textbf{\Large \sffamily?} & Digital Twin\newline Definition Language & Cloud Datacenter Engineers & { 3D\textsuperscript{$\star$}} \\ \midrule Reducio~\cite{DBLP:conf/sensys/CaoW0022} & POD, Gaussian\newline Process Modelling (ML) & {Heat Modelling} & Edge and Hyper-scale Datacenter Operators & {CH\textsuperscript{$\ddagger$}, 3D\textsuperscript{$\star$}}, SE \\ \midrule NetGraph~\cite{DBLP:conf/sigcomm/HongWDSSHZY21} & Graphs & Network Management & Cloud Datacenter Operators & VP\textsuperscript{$\star$}, RA\textsuperscript{$\star$}, N\textsuperscript{$\star$}, SE\textsuperscript{$\dagger$} \\ \midrule Kalibre~\cite{DBLP:conf/sensys/WangZD0TCWZ20} & CFD/HT, ML & {Heat Modelling} & Cloud Datacenter Engineers & {CH\textsuperscript{$\ddagger$}, 3D\textsuperscript{$\star$}} \\ \bottomrule \end{tabular} } \caption{Comparison of selected datacenter digital twins. \textbf{Modelling capability:} {3D = Visualizations}; {CH = Cooling/Heat}, PE = Power/Energy Consumption, A = Anomaly Detection, N = Network Modelling, SE = Scenario Exploration, VP = Virtual Prototyping, FD = Federation, RA = Resource Allocation; \textbf{Data Analytics}: $\ddagger$ = Predictive Analysis; $\star$ = Descriptive Analysis, $\dagger$ = Prescriptive Analysis.} \label{tab:dt_features_comparison} \end{table} % Autonomous decisions (autonomous twinning) from~\cite{DBLP:conf/sc/BrewerMKWBHSGGW24} is inherent to digital twinning -- it is better left unsaid in the table. % I.e., the foundation of any DT is autonomous decisions, so without them they don't qualify as a DT. % ChatTwin mentions that they evaluate their system on their own-engineered digital twin, but they absolutely not name it. Who knows why.