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garage/doc/talks/2024-02-03-fosdem/talk.tex
Alex Auvolat 76e09c0472
[talk-fosdem-24] small change in talk
2024-02-01 11:43:21 +01:00

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\nonstopmode
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\begin{frame}
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\centering
\begin{beamercolorbox}[sep=8pt,center,shadow=true,rounded=true]{title}
\usebeamerfont{title}\insertsectionhead\par%
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\title{Garage, the low-tech storage platform for geo-distributed clusters}
\author{Alex Auvolat, Deuxfleurs}
\date{FOSDEM'24, 2024-02-03}
\begin{document}
\begin{frame}
\centering
\includegraphics[width=.3\linewidth]{../../sticker/Garage.png}
\vspace{1em}
{\large\bf Alex Auvolat, Deuxfleurs Association}
\vspace{1em}
\url{https://garagehq.deuxfleurs.fr/}
Matrix channel: \texttt{\#garage:deuxfleurs.fr}
\end{frame}
\begin{frame}
\frametitle{Who I am}
\begin{columns}[t]
\begin{column}{.2\textwidth}
\centering
\adjincludegraphics[width=.4\linewidth, valign=t]{../assets/alex.jpg}
\end{column}
\begin{column}{.6\textwidth}
\textbf{Alex Auvolat}\\
PhD; co-founder of Deuxfleurs
\end{column}
\begin{column}{.2\textwidth}
~
\end{column}
\end{columns}
\vspace{2em}
\begin{columns}[t]
\begin{column}{.2\textwidth}
\centering
\adjincludegraphics[width=.5\linewidth, valign=t]{../assets/logos/deuxfleurs.pdf}
\end{column}
\begin{column}{.6\textwidth}
\textbf{Deuxfleurs}\\
A non-profit self-hosting collective,\\
member of the CHATONS network
\end{column}
\begin{column}{.2\textwidth}
\centering
\adjincludegraphics[width=.7\linewidth, valign=t]{../assets/logos/logo_chatons.png}
\end{column}
\end{columns}
\end{frame}
\begin{frame}
\frametitle{Our objective at Deuxfleurs}
\begin{center}
\textbf{Promote self-hosting and small-scale hosting\\
as an alternative to large cloud providers}
\end{center}
\vspace{2em}
\visible<2->{
Why is it hard?
}
\visible<3->{
\vspace{2em}
\begin{center}
\textbf{\underline{Resilience}}\\
{\footnotesize we want good uptime/availability with low supervision}
\end{center}
}
\end{frame}
\begin{frame}
\frametitle{Building a resilient system with cheap stuff}
\only<1,4-7>{
\begin{itemize}
\item \textcolor<5->{gray}{Commodity hardware (e.g. old desktop PCs)\\
\vspace{.5em}
\visible<4->{{\footnotesize (can die at any time)}}}
\vspace{1.5em}
\item<5-> \textcolor<7->{gray}{Regular Internet (e.g. FTTB, FTTH) and power grid connections\\
\vspace{.5em}
\visible<6->{{\footnotesize (can be unavailable randomly)}}}
\vspace{1.5em}
\item<7-> \textbf{Geographical redundancy} (multi-site replication)
\end{itemize}
}
\only<2>{
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/neptune.jpg}
\end{center}
}
\only<3>{
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/atuin.jpg}
\end{center}
}
\only<8>{
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/inframap_jdll2023.pdf}
\end{center}
}
\end{frame}
\begin{frame}
\frametitle{Object storage: a crucial component}
\begin{center}
\includegraphics[height=6em]{../assets/logos/Amazon-S3.jpg}
\hspace{3em}
\visible<2->{\includegraphics[height=5em]{../assets/logos/minio.png}}
\hspace{3em}
\visible<3>{\includegraphics[height=6em]{../../logo/garage_hires_crop.png}}
\end{center}
\vspace{1em}
S3: a de-facto standard, many compatible applications
\vspace{1em}
\visible<2->{MinIO is self-hostable but not suited for geo-distributed deployments}
\vspace{1em}
\visible<3->{\textbf{Garage is a self-hosted drop-in replacement for the Amazon S3 object store}}
\end{frame}
\begin{frame}
\frametitle{CRDTs / weak consistency instead of consensus}
\underline{Internally, Garage uses only CRDTs} (conflict-free replicated data types)
\vspace{2em}
Why not Raft, Paxos, ...? Issues of consensus algorithms:
\vspace{1em}
\begin{itemize}
\item<2-> \textbf{Software complexity}
\vspace{1em}
\item<3-> \textbf{Performance issues:}
\vspace{.5em}
\begin{itemize}
\item<4-> The leader is a \textbf{bottleneck} for all requests\\
\vspace{.5em}
\item<5-> \textbf{Sensitive to higher latency} between nodes
\vspace{.5em}
\item<6-> \textbf{Takes time to reconverge} when disrupted (e.g. node going down)
\end{itemize}
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{The data model of object storage}
Object storage is basically a \textbf{key-value store}:
\vspace{.5em}
{\scriptsize
\begin{center}
\begin{tabular}{|l|p{7cm}|}
\hline
\textbf{Key: file path + name} & \textbf{Value: file data + metadata} \\
\hline
\hline
\texttt{index.html} &
\texttt{Content-Type: text/html; charset=utf-8} \newline
\texttt{Content-Length: 24929} \newline
\texttt{<binary blob>} \\
\hline
\texttt{img/logo.svg} &
\texttt{Content-Type: text/svg+xml} \newline
\texttt{Content-Length: 13429} \newline
\texttt{<binary blob>} \\
\hline
\texttt{download/index.html} &
\texttt{Content-Type: text/html; charset=utf-8} \newline
\texttt{Content-Length: 26563} \newline
\texttt{<binary blob>} \\
\hline
\end{tabular}
\end{center}
}
\vspace{1em}
\begin{itemize}
\item<2> Maps well to CRDT data types
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Performance gains in practice}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/perf/endpoint_latency_0.7_0.8_minio.png}
\end{center}
\end{frame}
% ======================================== TIMELINE
% ======================================== TIMELINE
% ======================================== TIMELINE
\section{Recent developments}
% ====================== v0.7.0 ===============================
\begin{frame}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/timeline-22-24.pdf}
\end{center}
\end{frame}
\begin{frame}
\frametitle{April 2022 - Garage v0.7.0}
Focus on \underline{observability and ecosystem integration}
\vspace{2em}
\begin{itemize}
\item \textbf{Monitoring:} metrics and traces, using OpenTelemetry
\vspace{1em}
\item Replication modes with 1 or 2 copies / weaker consistency
\vspace{1em}
\item Kubernetes integration for node discovery
\vspace{1em}
\item Admin API (v0.7.2)
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Metrics (Prometheus + Grafana)}
\begin{center}
\includegraphics[width=.9\linewidth]{../assets/screenshots/grafana_dashboard.png}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Traces (Jaeger)}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/screenshots/jaeger_listobjects.png}
\end{center}
\end{frame}
% ====================== v0.8.0 ===============================
\begin{frame}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/timeline-22-24.pdf}
\end{center}
\end{frame}
\begin{frame}
\frametitle{November 2022 - Garage v0.8.0}
Focus on \underline{performance}
\vspace{2em}
\begin{itemize}
\item \textbf{Alternative metadata DB engines} (LMDB, Sqlite)
\vspace{1em}
\item \textbf{Performance improvements:} block streaming, various optimizations...
\vspace{1em}
\item Bucket quotas (max size, max \#objects)
\vspace{1em}
\item Quality of life improvements, observability, etc.
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{About metadata DB engines}
\textbf{Issues with Sled:}
\vspace{1em}
\begin{itemize}
\item Huge files on disk
\vspace{.5em}
\item Unpredictable performance, especially on HDD
\vspace{.5em}
\item API limitations
\vspace{.5em}
\item Not actively maintained
\end{itemize}
\vspace{2em}
\textbf{LMDB:} very stable, good performance, file size is reasonable\\
\textbf{Sqlite} also available as a second choice
\vspace{1em}
Sled will be removed in Garage v1.0
\end{frame}
\begin{frame}
\frametitle{DB engine performance comparison}
\begin{center}
\includegraphics[width=.6\linewidth]{../assets/perf/db_engine.png}
\end{center}
NB: Sqlite was slow due to synchronous mode, now configurable
\end{frame}
\begin{frame}
\frametitle{Block streaming}
\begin{center}
\only<1>{\includegraphics[width=.8\linewidth]{../assets/schema-streaming-1.png}}
\only<2>{\includegraphics[width=.8\linewidth]{../assets/schema-streaming-2.png}}
\end{center}
\end{frame}
\begin{frame}
\frametitle{TTFB benchmark}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/perf/ttfb.png}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Throughput benchmark}
\begin{center}
\includegraphics[width=.7\linewidth]{../assets/perf/io-0.7-0.8-minio.png}
\end{center}
\end{frame}
% ====================== v0.9.0 ===============================
\begin{frame}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/timeline-22-24.pdf}
\end{center}
\end{frame}
\begin{frame}
\frametitle{October 2023 - Garage v0.9.0}
Focus on \underline{streamlining \& usability}
\vspace{2em}
\begin{itemize}
\item Support multiple HDDs per node
\vspace{1em}
\item S3 compatibility:
\vspace{1em}
\begin{itemize}
\item support basic lifecycle configurations
\vspace{.5em}
\item allow for multipart upload part retries
\end{itemize}
\vspace{1em}
\item LMDB by default, deprecation of Sled
\vspace{1em}
\item New layout computation algorithm
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Layout computation}
\begin{overprint}
\onslide<1>
\begin{center}
\includegraphics[width=\linewidth, trim=0 0 0 -4cm]{../assets/screenshots/garage_status_0.9_prod_zonehl.png}
\end{center}
\onslide<2>
\begin{center}
\includegraphics[width=.7\linewidth]{../assets/map.png}
\end{center}
\end{overprint}
\vspace{1em}
Garage stores replicas on different zones when possible
\end{frame}
\begin{frame}
\frametitle{What a "layout" is}
\textbf{A layout is a precomputed index table:}
\vspace{1em}
{\footnotesize
\begin{center}
\begin{tabular}{|l|l|l|l|}
\hline
\textbf{Partition} & \textbf{Node 1} & \textbf{Node 2} & \textbf{Node 3} \\
\hline
\hline
Partition 0 & df-ymk (bespin) & Abricot (scorpio) & Courgette (neptune) \\
\hline
Partition 1 & Ananas (scorpio) & Courgette (neptune) & df-ykl (bespin) \\
\hline
Partition 2 & df-ymf (bespin) & Celeri (neptune) & Abricot (scorpio) \\
\hline
\hspace{1em}$\vdots$ & \hspace{1em}$\vdots$ & \hspace{1em}$\vdots$ & \hspace{1em}$\vdots$ \\
\hline
Partition 255 & Concombre (neptune) & df-ykl (bespin) & Abricot (scorpio) \\
\hline
\end{tabular}
\end{center}
}
\vspace{2em}
\visible<2->{
The index table is built centrally using an optimal algorithm,\\
then propagated to all nodes
}
\vspace{1em}
\visible<3->{
\footnotesize
Oulamara, M., \& Auvolat, A. (2023). \emph{An algorithm for geo-distributed and redundant storage in Garage}.\\ arXiv preprint arXiv:2302.13798.
}
\end{frame}
% ====================== v0.10.0 ===============================
\begin{frame}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/timeline-22-24.pdf}
\end{center}
\end{frame}
\begin{frame}
\frametitle{October 2023 - Garage v0.10.0 beta}
Focus on \underline{consistency}
\vspace{2em}
\begin{itemize}
\item Fix consistency issues when reshuffling data
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Working with weak consistency}
Not using consensus limits us to the following:
\vspace{2em}
\begin{itemize}
\item<2-> \textbf{Conflict-free replicated data types} (CRDT)\\
\vspace{1em}
{\footnotesize Non-transactional key-value stores such as S3 are equivalent to a simple CRDT:\\
a map of \textbf{last-writer-wins registers} (each key is its own CRDT)}
\vspace{1.5em}
\item<3-> \textbf{Read-after-write consistency}\\
\vspace{1em}
{\footnotesize Can be implemented using quorums on read and write operations}
\end{itemize}
\end{frame}
\begin{frame}[t]
\frametitle{CRDT read-after-write consistency using quorums}
\vspace{1em}
{\small
\textbf{Property:} If client 1 did an operation $write(x)$ and received an OK response,\\
\hspace{2cm} and client 2 starts an operation $read()$ after client 1 received OK,\\
\hspace{2cm} then client 2 will read a value $x' \sqsupseteq x$.
}
\vspace{1.5em}
\begin{overprint}
\onslide<2-9>
\begin{figure}
\centering
\footnotesize
\def\svgwidth{.7\textwidth}
\only<2>{\import{../assets/lattice/}{lattice1.pdf_tex}}%
\only<3>{\import{../assets/lattice/}{lattice2.pdf_tex}}%
\only<4>{\import{../assets/lattice/}{lattice3.pdf_tex}}%
\only<5>{\import{../assets/lattice/}{lattice4.pdf_tex}}%
\only<6>{\import{../assets/lattice/}{lattice5.pdf_tex}}%
\only<7>{\import{../assets/lattice/}{lattice6.pdf_tex}}%
\only<8>{\import{../assets/lattice/}{lattice7.pdf_tex}}%
\only<9>{\import{../assets/lattice/}{lattice8.pdf_tex}}%
\end{figure}
\onslide<10>
\begin{minipage}{.10\textwidth}
~
\end{minipage}
\begin{minipage}{.40\textwidth}
\footnotesize
\textbf{Algorithm $write(x)$:}
\begin{enumerate}
\item Broadcast $write(x)$ to all nodes
\item Wait for $k > n/2$ nodes to reply OK
\item Return OK
\end{enumerate}
\end{minipage}
\begin{minipage}{.40\textwidth}
\footnotesize
\vspace{1em}
\textbf{Algorithm $read()$:}
\begin{enumerate}
\item Broadcast $read()$ to all nodes
\item Wait for $k > n/2$ nodes to reply\\
with values $x_1, \dots, x_k$
\item Return $x_1 \sqcup \dots \sqcup x_k$
\end{enumerate}
\end{minipage}
\end{overprint}
\end{frame}
\begin{frame}
\frametitle{A hard problem: layout changes}
\begin{itemize}
\item We rely on quorums $k > n/2$ within each partition:\\
$$n=3,~~~~~~~k\ge 2$$
\item<2-> When rebalancing, the set of nodes responsible for a partition can change:\\
\vspace{1em}
\begin{minipage}{.04\linewidth}~
\end{minipage}
\begin{minipage}{.40\linewidth}
{\tiny
\begin{tabular}{|l|l|l|l|}
\hline
\textbf{Partition} & \textbf{Node 1} & \textbf{Node 2} & \textbf{Node 3} \\
\hline
\hline
Partition 0 & \textcolor{Crimson}{df-ymk} & Abricot & \textcolor{Crimson}{Courgette} \\
\hline
Partition 1 & Ananas & \textcolor{Crimson}{Courgette} & \textcolor{Crimson}{df-ykl} \\
\hline
Partition 2 & \textcolor{Crimson}{df-ymf} & \textcolor{Crimson}{Celeri} & Abricot \\
\hline
\hspace{1em}$\dots$ & \hspace{1em}$\dots$ & \hspace{1em}$\dots$ & \hspace{1em}$\dots$ \\
\hline
\end{tabular}
}
\end{minipage}
\begin{minipage}{.04\linewidth}
$\to$
\end{minipage}
\begin{minipage}{.40\linewidth}
{\tiny
\begin{tabular}{|l|l|l|l|}
\hline
\textbf{Partition} & \textbf{Node 1} & \textbf{Node 2} & \textbf{Node 3} \\
\hline
\hline
Partition 0 & \textcolor{ForestGreen}{Dahlia} & Abricot & \textcolor{ForestGreen}{Eucalyptus} \\
\hline
Partition 1 & Ananas & \textcolor{ForestGreen}{Euphorbe} & \textcolor{ForestGreen}{Doradille} \\
\hline
Partition 2 & \textcolor{ForestGreen}{Dahlia} & \textcolor{ForestGreen}{Echinops} & Abricot \\
\hline
\hspace{1em}$\dots$ & \hspace{1em}$\dots$ & \hspace{1em}$\dots$ & \hspace{1em}$\dots$ \\
\hline
\end{tabular}
}
\end{minipage}
\vspace{2em}
\item<3-> During the rebalancing, new nodes don't yet have the data,\\
~~~~~~~~~~~~~~~~~~~and old nodes want to get rid of the data to free up space\\
\vspace{1.2em}
$\to$ risk of inconsistency, \textbf{how to coordinate?}
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Handling layout changes without losing consistency}
\begin{minipage}{.55\textwidth}
\begin{itemize}
\item \textbf{Solution:}\\
\vspace{.5em}
\begin{itemize}
\item keep track of data transfer to new nodes
\vspace{.5em}
\item use multiple write quorums\\
(new nodes + old nodes\\
while data transfer is in progress)
\vspace{.5em}
\item switching reads to new nodes\\
only once copy is finished
\end{itemize}
\vspace{1em}
\item \textbf{Implemented} in v0.10
\vspace{1em}
\item \textbf{Validated} with Jepsen testing
\end{itemize}
\end{minipage}
\begin{minipage}{.23\textwidth}
\includegraphics[width=3cm]{../assets/jepsen-0.9.png}\\
{\footnotesize Garage v0.9.0}
\end{minipage}
\begin{minipage}{.2\textwidth}
\includegraphics[width=3cm]{../assets/jepsen-0.10.png}\\
{\footnotesize Garage v0.10 beta}
\end{minipage}
\end{frame}
% ====================== v0.10.0 ===============================
\begin{frame}
\begin{center}
\includegraphics[width=.8\linewidth]{../assets/timeline-22-24.pdf}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Towards v1.0...}
Focus on \underline{security \& stability}
\vspace{2em}
\begin{itemize}
\item \textbf{Security audit} in progress by Radically Open Security
\vspace{1em}
\item Misc. S3 features (SSE-C, ...) and compatibility fixes
\vspace{1em}
\item Improve UX
\vspace{1em}
\item Fix bugs
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{...and beyond!}
\begin{center}
\includegraphics[width=.6\linewidth]{../assets/survey_requested_features.png}
\end{center}
\end{frame}
% ======================================== OPERATING
% ======================================== OPERATING
% ======================================== OPERATING
\section{Operating big Garage clusters}
\begin{frame}
\frametitle{Operating Garage}
\begin{center}
\only<1-2>{
\includegraphics[width=.9\linewidth]{../assets/screenshots/garage_status_0.10.png}
\\\vspace{1em}
\visible<2>{\includegraphics[width=.9\linewidth]{../assets/screenshots/garage_status_unhealthy_0.10.png}}
}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Garage's architecture}
\begin{center}
\only<1>{\includegraphics[width=.45\linewidth]{../assets/garage.drawio.pdf}}%
\only<2>{\includegraphics[width=.6\linewidth]{../assets/garage_sync.drawio.pdf}}%
\end{center}
\end{frame}
\begin{frame}
\frametitle{Digging deeper}
\begin{center}
\only<1>{\includegraphics[width=.9\linewidth]{../assets/screenshots/garage_stats_0.10.png}}
\only<2>{\includegraphics[width=.5\linewidth]{../assets/screenshots/garage_worker_list_0.10.png}}
\only<3>{\includegraphics[width=.6\linewidth]{../assets/screenshots/garage_worker_param_0.10.png}}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Potential limitations and bottlenecks}
\begin{itemize}
\item Global:
\begin{itemize}
\item Max. $\sim$100 nodes per cluster (excluding gateways)
\end{itemize}
\vspace{1em}
\item Metadata:
\begin{itemize}
\item One big bucket = bottleneck, object list on 3 nodes only
\end{itemize}
\vspace{1em}
\item Block manager:
\begin{itemize}
\item Lots of small files on disk
\item Processing the resync queue can be slow
\end{itemize}
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Deployment advice for very large clusters}
\begin{itemize}
\item Metadata storage:
\begin{itemize}
\item ZFS mirror (x2) on fast NVMe
\item Use LMDB storage engine
\end{itemize}
\vspace{.5em}
\item Data block storage:
\begin{itemize}
\item Use Garage's native multi-HDD support
\item XFS on individual drives
\item Increase block size (1MB $\to$ 10MB, requires more RAM and good networking)
\item Tune \texttt{resync-tranquility} and \texttt{resync-worker-count} dynamically
\end{itemize}
\vspace{.5em}
\item Other :
\begin{itemize}
\item Split data over several buckets
\item Use less than 100 storage nodes
\item Use gateway nodes
\end{itemize}
\vspace{.5em}
\end{itemize}
Our deployments: $< 10$ TB. Some people have done more!
\end{frame}
% ======================================== END
% ======================================== END
% ======================================== END
\begin{frame}
\frametitle{Where to find us}
\begin{center}
\includegraphics[width=.25\linewidth]{../../logo/garage_hires.png}\\
\vspace{-1em}
\url{https://garagehq.deuxfleurs.fr/}\\
\url{mailto:garagehq@deuxfleurs.fr}\\
\texttt{\#garage:deuxfleurs.fr} on Matrix
\vspace{1.5em}
\includegraphics[width=.06\linewidth]{../assets/logos/rust_logo.png}
\includegraphics[width=.13\linewidth]{../assets/logos/AGPLv3_Logo.png}
\end{center}
\end{frame}
\end{document}
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