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Cloud Architecture Tutorial - Running in the Cloud (3of3)
The document discusses cloud architecture and deployment strategies utilized by Netflix, detailing their capacity planning, cloud testing, and workload management. It emphasizes the importance of monitoring scalability, availability, and resilience while transitioning services from on-premises to cloud platforms. Additionally, the complexities of managing varying workloads and the optimizations made in their use of Cassandra for data management are highlighted.
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Cloud Architecture Tutorial - Running in the Cloud (3of3)
- 1. Cloud Architecture Tutorial Running in the Cloud Qcon London March 5th, 2012 Adrian Cockcro6 @adrianco #ne:lixcloud h>p://www.linkedin.com/in/adriancockcro6 Part 3 of 3
- 2. Running in the Cloud Bring-‐up Strategy for Developers and TesRng Capacity Planning and Workloads Running Cassandra Monitoring and Scalability Availability and Resilience OrganizaRonal Structure
- 3. Cloud Bring-‐Up Strategy Simplest and Soonest
- 4. Shadow Traffic RedirecRon • Early a>empt to send traffic to cloud – Real traffic stream to validate cloud back end – Uncovered lots of process and tools issues – Uncovered Service latency issues • TV Device calls Datacenter API and Cloud API – Returns Genre/movie list for a customer – Asynchronously duplicate request to cloud – Start with send-‐and-‐forget mode, ignore response
- 5. Shadow Redirect Instances Modified Datacenter Datacenter Service Instances Modified Cloud Cloud Service One request per Instances visit Data Sources queueservice videometadata
- 6. Video Metadata Server • VMS instance isolates new pla:orm from old codebase – Isolate/unblock cloud team from metadata team schedule – Datacenter code supports obsolete movie object – VMS ESL is designed to support new video facet object • VMS subsets and pre-‐processes the metadata – Only load data used by cloud services – Fast bulk loads for VMS clients speed startup Rmes – Explore next generaRon metadata cache architecture Pa$ern – Add services to isolate old and new code base
- 7. First Web Pages in the Cloud
- 8. First Page • First full page – Basic Genre – Simplest page, no sub-‐genres, minimal personalizaRon – Lots of investment in new Struts based page design – Uses idenRty cookie to lookup in member info svc • New “merchweb” front end instance – movies.ne:lix.com points to merchweb instance • Uncovered lots of latency issues – Used memcached to hide S3 and SimpleDB latency – Improved from slower to faster than Datacenter
- 9. Genre Page Cloud Instances Front End merchweb mulRple requests Middle Tier genre memcached per visit Data Sources queueservice rentalhistory videometadata
- 10. Controlled Cloud TransiRon • WWW calling code chooses who goes to cloud – Filter out corner cases, send percentage of users – The URL that customers see is h>p://movies.ne:lix.com/WiContentPage?csid=1 – If problem, redirect to old Datacenter page h>p://www.ne:lix.com/WiContentPage?csid=1 • Play Bu>on and Star RaRng AcRon redirect – Point URLs for acRons that create/modify data back to datacenter to start with
- 11. Cloud Development and TesRng Issues
- 12. Boot Camp • One day “Ne:lix Cloud Training” class – Has been run 6 Rmes for 20-‐45 people each Rme • Half day of presentaRons • Half day hands-‐on – Create your own hello world app – Launch in AWS test account – Login to your cloud instances – Find monitoring data on your cloud instances – Connect to Cassandra and read/write data
- 13. Very First Boot Camp • Pathfinder Bootstrap Mission – Room full of engineers sharing the pain for 1-‐2 days – Built a very rough prototype working web site • Get everyone hands-‐on with a new code base – Debug lots of tooling and conceptual issues very fast – Used SimpleDB to create mock data sources • Cloud Specific Key Setup – Needed to integrate with AWS security model – New concepts for datacenter developers
- 14. Developer Instances Collision Sam and Rex both want to deploy web front end for development Sam Rex web in test account
- 15. Per-‐Service Namespace Stack RouRng Developers choose what to share Sam Rex Mike web-‐sam web-‐rex web-‐dev backend-‐dev backend-‐dev backend-‐mike
- 16. Developer Namespace Stacks • Developer specific service instances – Configured via Java properRes at runRme – RouRng implemented by REST client library • Server ConfiguraRon – Configure discovery service version string – Registers as <appname>-‐<namespace> • Client ConfiguraRon – Route traffic on per-‐service basis including namespace
- 17. Capacity Planning Metrics and Methods
- 18. What is Capacity Planning • We care about – CPU, Memory, Network and Disk resource uRlizaRon – ApplicaRon response Rmes and throughput • We need to know – how much of each resource we are using now, and will use in the future – how much headroom we have to handle higher loads • We want to understand – how headroom varies – how it relates to applicaRon response Rmes and throughput
- 19. Capacity Planning Norms • Capacity is expensive • Capacity takes Rme to buy and provision • Capacity only increases, can’t be shrunk easily • Capacity comes in big chunks, paid up front • Planning errors can cause big problems • Systems are clearly defined assets • Systems can be instrumented in detail • Depreciate assets over 3 years
- 20. Capacity Planning in Clouds (a few things have changed…) • Capacity is expensive • Capacity takes Rme to buy and provision • Capacity only increases, can’t be shrunk easily • Capacity comes in big chunks, paid up front • Planning errors can cause big problems • Systems are clearly defined assets • Systems can be instrumented in detail • Depreciate assets over 3 years (reservaRons!)
- 21. Capacity is expensive h>p://aws.amazon.com/s3/ & h>p://aws.amazon.com/ec2/ • Storage (Amazon S3) – $0.125 per GB – first 50 TB / month of storage used – $0.055 per GB – storage used / month over 5 PB • Data Transfer (Amazon S3) – $0.000 per GB – all data transfer in is free, first GB out is free – $0.120 per GB – first 10 TB / month data transfer out – $0.050 per GB – data transfer out / month over 350 TB • Requests (Amazon S3 Storage access is via h>p) – $0.01 per 1,000 PUT, COPY, POST, or LIST requests – $0.01 per 10,000 GET and all other requests – $0 per DELETE • CPU (Amazon EC2) – Small (Default) $0.085/hour, Extra Large $0.68/hour, Four XL $2.00/hour – Small (Default) $0.08/hour, Extra Large $0.64/hour, Four XL $1.80/hour • Network (Amazon EC2) – Inbound/Outbound around $0.10 per GB
- 22. Capacity comes in big chunks, paid up front • Capacity takes Rme to buy and provision – No minimum price, monthly billing – “Amazon EC2 enables you to increase or decrease capacity within minutes, not hours or days. You can commission one, hundreds or even thousands of server instances simultaneously” • Capacity only increases, can’t be shrunk easily – Pay for what is actually used • Planning errors can cause big problems – Size only for what you need now
- 23. Systems are clearly defined assets • You are running in a “stateless” mulR-‐ tenanted virtual image that can die or be taken away and replaced at any Rme • You don’t know exactly where it is, you can choose to locate “US-‐East” or “Europe” etc. • You can specify zones that will not share components to avoid common mode failures
- 24. Systems can be instrumented in detail • Each cloud node allocaRon is unique – So elasRc usage pa>erns keep creaRng new nodes – “garbage collect” nodes that won’t be seen again – Need to map EIP and Cassandra tokens to instances • Ne:lix SoluRon – Entrypoints Slots – Each Autoscale Group has a size – Each instance is given a slot number up to size – Replacements pick empty slots
- 25. Depreciate assets over 3 years (reservaRons!) • Reduced costs in return for commitment • One or three years, upfront payment • Payment can be depreciated as capital asset • Low, medium or high usage reservaRons – Save more if you use them more • Spot market instances – Unused reservaRons sold to other users cheap – Will be yanked at any Rme if needed
- 26. A Discussion of Workloads and How They Behave
- 27. Workload CharacterisRcs • A quick tour through a taxonomy of workload types • Start with the easy ones and work up • Why personalized workloads are different and hard • Some examples and coping strategies 3/12/12 Slide 176
- 28. Simple Random Arrivals • Random arrival of transacRons with fixed mean service Rme – Li>le’s Law: QueueLength = Throughput * Response – URlizaRon Law: URlizaRon = Throughput * ServiceTime • Complex models are o6en reduced to this model – By averaging over longer Rme periods since the formulas only work if you have stable averages – By wishful thinking (i.e. how to fool yourself) 3/12/12 Slide 177
- 29. Mixed random arrivals of transacRons with stable mean service Rmes • Think of the grocery store checkout analogy – Trolleys full of shopping vs. baskets full of shopping – Baskets are quick to service, but get stuck behind carts – RelaRve mixture of transacRon types starts to ma>er • Many transacRonal systems handle a mixture – Databases, web services • Consider separaRng fast and slow transacRons – So that we have a “10 items or less” line just for baskets – Separate pools of servers for different services – The old rule -‐ don’t mix OLTP with DSS queries in databases • Performance is o6en thread-‐limited – Thread limit and slow transacRons constrains maximum throughput • Model mix using analyRcal solvers (e.g. PDQ perfdynamics.com) 3/12/12 Slide 178
- 30. Load dependent servers – varying mean service Rmes • Mean service Rme may increase at high throughput – Due to non-‐scalable algorithms, lock contenRon – System runs out of memory and starts paging or frequent GC • Mean service Rme may also decrease at high throughput – Elevator seek and write cancellaRon opRmizaRons in storage – Load shedding and simplified fallback modes • Systems have “Rpping points” if the service Rme increases – Hysteresis means they don’t come back when load drops – This is why you have to kill catatonic systems – Best designs shed load to be stable at the limit – circuit breaker pa>ern – PracRcal opRon is to try to avoid Rpping points by reducing variance • Model using discrete event simulaRon tools – Behaviour is non-‐linear and hard to model 3/12/12 Slide 179
- 31. Self-‐similar / fractal workloads • Bursty rather than random arrival rates • Self-‐similar – Looks “random” at close up, stays “random” as you zoom out – Work arrives in bursts, transacRons aren’t independent – Bursts cluster together in super-‐bursts, etc. • Network packet streams tend to be fractal • Common in pracRce, too hard to model – Probably the most common reason why your model is wrong! 3/12/12 Slide 180
- 32. State Dependent Service Workloads • Personalized services that store user state/history – TransacRons for new users are quick – TransacRons for users with lots of state/history are slower – As user base builds state and ages you get into trouble… • Social Networks, RecommendaRon Services – Facebook, Flickr, Ne:lix, Twi>er etc. • “Abandon hope all ye who enter here” – Not tractable to model, repeatable tests are tricky – Long fat tail response Rme distribuRon and Rmeouts • Try to transform workloads to more tractable forms 3/12/12 Slide 181
- 33. Example -‐ Twi>er Workload • @adrianco tweets – copy to 3600 or so other users • @zoecello tweets many Rmes a day – to over 1M users • @barackobama tweets every few days – to over 12M users • It’s the same transacRon, but the service Rme varies by several orders of magnitude • The best (most acRve and connected = most valuable) users trigger a “denial of service a>ack” on the systems when they tweet • Cascading effect as many others re-‐tweet 3/12/12 Slide 182
- 34. Example -‐ Ne:lix Movie Choosing • “Pick 24 genres/subgenres etc. of 75 movies each for me” – used by TV based devices like Xbox360, PS/3, iPhone app • New user – No history of what they have rented (DVD) or streamed – No star raRngs for movies, possibly some genre raRngs – Basic demographic info – Fast to calculate, easy to find many good choices to return • User with several years tenure – Thousands of movies rented or streamed, “seen it already” – Hundreds to thousands of star raRngs, lots of genre raRngs – Requests may Rme out and return fewer or worse choices 3/12/12 Slide 183
- 35. Workload Modelling Survival Methods • Simplify the workload algorithms – move from hard or impossible to simpler models – decouple, cache and pre-‐compute to get constant service Rmes • Stand further away – averaging is your friend – gets rid of complex fluctuaRons • Minimalist Models – most models are far too complex – the classic beginners error… – the art of modelling is to only model what really ma>ers • Don’t model details you don’t use – model peak hour of the week, not day to day fluctuaRons – e.g. “Will the web site survive next Sunday night?” 3/12/12 Slide 184
- 36.
- 37. Cassandra Use Cases • Key by Customer – Cross-‐region clusters – Many app specific Cassandra clusters, read-‐intensive – Keys+Rows in memory using m2.4xl Instances • Key by Customer:Movie – e.g. Viewing History – Growing fast, write intensive – m1.xl instances – Keys cached in memory, one cluster per region • Large scale data logging – lots of writes – Column data expires a6er Rme period – Distributed counters, one cluster per region
- 38. Ne:lix Pla:orm Cassandra AMI • Tomcat server with Priam – Always running, registers with pla:orm – Manages Cassandra state, tokens, backups • Removed Root Disk Dependency on EBS – Use S3 backed AMI for stateful services – Normally use EBS backed AMI for fast provisioning
- 39. Ne:lix ContribuRons to Cassandra • Cassandra as a mutable toolkit – Cassandra is in Java, pluggable, well structured – Ne:lix has a building full of Java engineers…. – We changed Cassandra to make it run much be>er on AWS • ContribuRons delivered to Cassandra – 0.8 Prototype off-‐heap row cache, SSTable write callback – 1.x OpRmizaRons reduced impact of repair & compacRon – January 2012 – Ne:lix engineer becomes core commi>er • Cassandra Based Projects on github.com/Ne:lix – Priam AWS integraRon and backup using Tomcat helper – Astyanax Java client library – CassJMeter for performance and regression tesRng
- 40.
- 41. Monitoring Vision • Problem – Too many tools, each with a good reason to exist – Hard to get an integrated view of a problem – Too much manual work building dashboards – Tools are not discoverable, views are not filtered • SoluRon – Get vendors to add deep linking and embedding – IntegraRon “portal” Res everything together – Dynamic portal generaRon, relevant data, all tools
- 42. Cloud Monitoring Mechanisms • Keynote or Gomez etc. – External URL monitoring • Amazon CloudWatch – Metrics for ELB and Instances • AppDynamics – End to end transacRon view showing resources used – Powerful real Rme debug tools for latency, CPU and Memory • Epic (Ne:lix in-‐house project) – Flexible and easy to use to extend and embed plots • Logs – High capacity logging and analysis framework – Hadoop (log4j -‐> Honu -‐> EMR)
- 43. Using AppDynamics (simple example from early 2010)
- 44. AppDynamics Monitoring of Cassandra – AutomaRc Discovery
- 45. Scalability TesRng • Cloud Based TesRng – fricRonless, elasRc – Create/destroy any sized cluster in minutes – Many test scenarios run in parallel • Test Scenarios – Internal app specific tests – Simple “stress” tool provided with Cassandra • Scale test, keep making the cluster bigger – Check that tooling and automaRon works… – How many ten column row writes/sec can we do?
- 46.
- 47. Scale-‐Up Linearity h>p://techblog.ne:lix.com/2011/11/benchmarking-‐cassandra-‐scalability-‐on.html Client Writes/s by node count – Replica:on Factor = 3 1200000 1099837 1000000 800000 600000 537172 400000 366828 200000 174373 0 0 50 100 150 200 250 300 350
- 48. Stress Client Latency Includes ~10ms Scheduling Overhead – for be>er latency data see h>p://techblog.ne:lix.com/2012/03/jmeter-‐plugin-‐for-‐cassandra.html
- 49. Measured at the Cassandra Server 3.3 Million writes/sec at 0.014ms – 14 microseconds
- 50. Per Node AcRvity Per Node 48 Nodes 96 Nodes 144 Nodes 288 Nodes Per Server Writes/s 10,900 w/s 11,460 w/s 11,900 w/s 11,456 w/s Mean Server Latency 0.0117 ms 0.0134 ms 0.0148 ms 0.0139 ms Mean CPU %Busy 74.4 % 75.4 % 72.5 % 81.5 % Disk Read 5,600 KB/s 4,590 KB/s 4,060 KB/s 4,280 KB/s Disk Write 12,800 KB/s 11,590 KB/s 10,380 KB/s 10,080 KB/s Network Read 22,460 KB/s 23,610 KB/s 21,390 KB/s 23,640 KB/s Network Write 18,600 KB/s 19,600 KB/s 17,810 KB/s 19,770 KB/s Node specificaRon – Xen Virtual Images, AWS US East, three zones • Cassandra 0.8.6, CentOS, SunJDK6 • AWS EC2 m1 Extra Large – Standard price $ 0.68/Hour • 15 GB RAM, 4 Cores, 1Gbit network • 4 internal disks (total 1.6TB, striped together, md, XFS)
- 51. Time is Money 48 nodes 96 nodes 144 nodes 288 nodes Writes Capacity 174373 w/s 366828 w/s 537172 w/s 1,099,837 w/s Storage Capacity 12.8 TB 25.6 TB 38.4 TB 76.8 TB Nodes Cost/hr $32.64 $65.28 $97.92 $195.84 Test Driver Instances 10 20 30 60 Test Driver Cost/hr $20.00 $40.00 $60.00 $120.00 Cross AZ Traffic 5 TB/hr 10 TB/hr 15 TB/hr 301 TB/hr Traffic Cost/10min $8.33 $16.66 $25.00 $50.00 Setup DuraRon 15 minutes 22 minutes 31 minutes 662 minutes AWS Billed DuraRon 1hr 1hr 1 hr 2 hr Total Test Cost $60.97 $121.94 $182.92 $561.68 1 EsRmate two thirds of total network traffic 2 Workaround for a tooling bug slowed setup
- 52.
- 53. Chaos Monkey • Computers (Datacenter or AWS) randomly die – Fact of life, but too infrequent to test resiliency • Test to make sure systems are resilient – Allow any instance to fail without customer impact • Chaos Monkey hours – Monday-‐Thursday 9am-‐3pm random instance kill • ApplicaRon configuraRon opRon – Apps now have to opt-‐out from Chaos Monkey
- 54. Responsibility and Experience • Make developers responsible for failures – Then they learn and write code that doesn’t fail • Use Incident Reviews to find gaps to fix – Make sure its not about finding “who to blame” • Keep Rmeouts short, fail fast – Don’t let cascading Rmeouts stack up • Make configuraRon opRons dynamic – You don’t want to push code to tweak an opRon
- 55. Resilient Design – Circuit Breakers h>p://techblog.ne:lix.com/2012/02/fault-‐tolerance-‐in-‐high-‐volume.html
- 56. PaaS OperaRonal Model -‐ NoOps • Developers – Provision and run their own code in producRon – Take turns to be on call if it breaks (pagerduty) – Configure autoscalers to handle capacity needs • Difference between DevOps and NoOps – DevOps is about Dev and Ops working together – NoOps constrains Dev to use automaRon instead – NoOps puts more responsibility on Dev, with tools
- 57. ImplicaRons for IT OperaRons • Cloud is run by developer organizaRon – Our IT department is the AWS API – We have no IT staff working on cloud (they do corp IT) • Cloud capacity is 10x bigger than Datacenter – Datacenter oriented IT staffing is flat – We have moved a few people out of IT to write code • TradiRonal IT Roles are going away – Don’t need SA, DBA, Storage, Network admins – Developers deploy and run what they wrote in producRon
- 58. Ne:lix “NoOps” OrganizaRon Developer Org ReporRng into Product Development, not ITops Ne:lix Cloud Pla:orm Team Cloud Ops Build Tools Database Pla:orm Cloud Cloud Reliability and Engineering Development Performance SoluRons Engineering AutomaRon Perforce Jenkins Pla:orm jars Cassandra ArRfactory JIRA Benchmarking Monitoring Alert RouRng Key store Cassandra Monkeys Incident Lifecycle Base AMI, Bakery Zookeeper JVM GC Tuning Ne:lix App Console Wiresharking Entrypoints Astyanix PagerDuty AWS Instances AWS API AWS Instances AWS Instances AWS Instances
- 59. Wrap Up Answer your remaining quesRons… What was missing that you wanted to cover?
- 60. Takeaway Ne5lix has built and deployed a scalable global Pla5orm as a Service. Key components of the Ne5lix PaaS are being released as Open Source projects so you can build your own custom PaaS. h>p://github.com/Ne:lix h>p://techblog.ne:lix.com h>p://slideshare.net/Ne:lix h>p://www.linkedin.com/in/adriancockcro6 @adrianco #ne:lixcloud End of Part 3 of 3