THE DATACENTER AS A COMPUTER AND COURSE REVIEW

Transcription

1 THE DATACENTER A A COMPUTER AND COURE REVIEW George Porter June 8, 2018 ATTRIBUTION These slides are released under an Attribution-NonCommercial-hareAlike 3.0 Unported (CC BY-NC-A 3.0) Creative Commons license These slides incorporate material from: The Datacenter as a Computer: An Introduction to the Design of Warehouse-cale Machines, 2nd ed., by Barroso, Clidaras, and Hölzle. 1

2 OUTLINE 1. Power-proportional computing 2. Networking and power 3. Review 4. Open discussion / questions POWER-PROPORTIONAL HUMAN Barroso and Holzle, The Data Center as a Computer: An introduction to the Design of Warehouse-cale Machines 2

3 WEB-ERVICE LOAD FLUCTUATION Barroso and Holzle, The Data Center as a Computer: An introduction to the Design of Warehouse-cale Machines DO DIFFERENT COMPONENT CALE IMILARLY? Barroso and Holzle, The Data Center as a Computer: An introduction to the Design of Warehouse-cale Machines 3

4 CPU UTILIZATION Barroso and Holzle, The Data Center as a Computer: An introduction to the Design of Warehouse-cale Machines WHAT ABOUT POWER AVING FEATURE ON MODERN COMPUTER? 4

5 POWER TAKEAWAY Cloud computing has huge energy/cost implications Yet its very scalability is a way to improve world-wide efficiency compared to many small deployments Efficiency via high utilization Avoid power savings on a per-component basis Instead run system as close to 100% utilization as possible Challenges to 100% utilization oftware design / performance / choice of algorithms Network bottlenecks OUTLINE 1. Power-proportional computing 2. Networking and power 3. Review 4. Open discussion / questions 5

6 TRADITIONAL DC TOPOLOGY Core Internet Layer-3 router Data Center Aggregation Layer-2/3 switch Access Layer-2 switch ervers Tree-based network topologies Can t buy sufficiently fast core switches! 100,000 x 10 Gb/s = 1 Pb/s 12 6

7 DC Network Requirements calability Incremental build out? Reliability Loop free forwarding VM migration Reasonable management burden Humans in the loop? 13 Layer 2 Pods w/l3 Backbone Internet DC-Layer 3 DC-Layer 2 CR CR AR AR... AR AR... ~ 1,000 servers/pod == IP subnet Key CR = Core Router (L3) AR = Access Router (L3) = Ethernet witch (L2) A = Rack of app. servers 14 7

8 CAPACITY BOTTLENECK CR CR ~ 200:1 AR AR AR AR ~ 40:1 ~ 5:1... Discussion: Implications for energy efficiency? Recall: Folded-Clos multi-rooted Trees Al Fares, et al., igcomm Gb/s witches Core Aggregation Edge Gb/s servers Pod Pod 1 Pod 2 Pod

9 OUTLINE 1. Power-proportional computing 2. Networking and power 3. Review 4. Open discussion / questions NETWORK PROGRAMMING FUNDAMENTAL Network sockets API: open(), connect(), send(), recv(), etc How names are resolved to addresses in DN End to end protocols Move from host-to-host to process-to-process communication model TCP provide abstraction of reliable in-order byte stream on top of IP protocol ignals and timeouts Concurrency, multi-tasking, multiplexing Locking, mutexes, sharing state between threads/processes 9

10 PROTOCOL DEIGN AND ANALYI Framing vs. parsing Delimiter vs. length-value erver-side protocol handling Request for comments documents (RFCs) Deep dive on HTTP RPC Explain concept of 'idempotent' Maybe vs at least once vs at most once semantics; how to implement each of these? grpc Role of stub compiler, RPC runtimes Discuss whether the following operations are idempotent: Pressing a lift (elevator) request button Writing data to an offset in a file Appending data to the end of a file (assuming there are no other writers in the system) 10

11 REPLICA CONITENCY AND FAULT TOLERANCE Lamport clocks, vector clocks, time synchronization Replicated state machines/logs Two-phase commit Two-phase locking OVERLAY NETWORK, P2P, CHORD Compare and contrast aspects of flooding queries vs structured. Tradeoffs--which is better for joining, leaving, advertising content, querying for content. Assume you have a Chord system of 16 or 32 nodes with identifiers provided of the data and the servers Draw the identifier circle and show which nodes the keys will be assigned to Be able to perform lookups provided an example with finger tables provided Each chord node must maintain routing state. Describe exactly what routing state must be maintained at each node to ensure correct function. how what this state would be for a particular node. What is the expected lookup time of an object? Describe what routing state must be maintained at each node to ensure fast lookup times. how what this state would be for that node. what is the expected lookup time of an object? 11

12 DATA CENTER AND CDN Round-robin DN vs load balancers. advantages and disadvantages of each Replication vs partitioning: advantages and disadvantages Terms: MTTR, MTBF, availability, yield, harvest, DQ principle Terms: top of rack switch, PUE, PUE Tail latency vs. average latency Energy and power MAJOR TAKE-AWAY You can now Write software that any one in the world can access Deploy on the cloud for free Cloud providers offer (limited) free credits to students! Distributed geographically Reliable, fault-tolerant, secure (take 124/227...) Understanding the impact of that software on resources usage (energy, pollution) o go do it! 12

13 OUTLINE 1. Power-proportional computing 2. Networking and power 3. Review 4. Open discussion / questions TOPIC UMMARY Protocols, framing, parsing, layering ockets programming, IP, DN HTTP and web torage RPCs Time and causality Two-phase commit Consensus, replicated state machines Locking, concurrency control, locking, recovery Performance at scale CDNs P2P networks, Chord, DHTs Overlay networks Datacenters 13

14 THANK YOU FOR A GREAT COURE! 14