By: Brian King at Pearson Education

1. Writing Space
and the
Cassandra NoSQL DBMS
Brian King
(with thanks to Michael Aillon)

2. Writing Space

3. “Writing is one of the most effective tools
available to develop a student's critical thinking.”
Why A Writing Space?

4. • Efficient Administration Of Writing Assignments
• Scalable Classrooms (500+)
• Workflow Optimization / Automation
• Integrated Access to Assessment Tools
o Grammar Checking
o Auto-Scoring
o Plagiarism Detection (Source Check)
• Grading Rubrics
• Online Editing and Document Upload
• Peer Review
• Group Projects
The Business Needs

5. • Highly "Internet" Scalable
• Global Presence
• Continuous Availability (Fault Tolerance)
• Broad OS And Browser Support
• Mobile Device Support - "Mobile First"
• Low Cost (Systems, Maintenance, Integration)
• Write Once, Integrate “Anywhere”
• Gain Experience With Modern NoSQL Technologies
• REST Service-Based Architecture
• Model UI
The Technical Goals

6. Writing Space - Instructor

7. Writing Space - Student

8. Cassandra

9. • Highly Scalable
• Easy Multi-Data Center Support
• Performance
• Distributed Ring Configuration (Master-less)
• Dynamic Schema, “Schema-less”
• Slice Queries
What We Like

10. • Eventual / Tunable Consistency
• Key-Name-Value Data Store (Column Based)
• Data Modeling Based On Core Queries
• All Rows in a CF Typically Don't Live On 1 Server
• However, All Columns For a Row Do
• RDBMS Mindset
• No Ad Hoc Queries
What Challenged Us

11. What Is Consistency?
• Write Consistency: Number Of Replicas Written To
• Read Consistency: Number Of Replicas Queried
• Replication Factor: Number Of Replicas For A Row
• Quorum Consistency Level (Read And Write):
o Option In Specifying Read/Write Consistency
o (Replication_Factor / 2) + 1
o Ensures Strong Consistency
o While Maintaining High Availability
• With 4 Servers, Writing Space uses:
o Replication Factor = 3
o Read and Write Quorum Consistency

12. Typical RDBMS Features Not Available (Yet):
• Referential Integrity Constraints / Foreign Keys
• Commit / Rollback
• Stored Procedures
• Joins
• Views
• Triggers
• Functions
• Security Privileges
• Rules
• Partitioned Table Definitions
What's Not In Cassandra...

13. Cassandra
In
Writing Space

14. Document Versioning...

15. How We Modeled Our Data...
Storage Strategy: Document-oriented
1:M
1:1

16. The Writing Space
DB Infrastructure

17. The Hardware
• Many Inexpensive Servers (Actually 4 + 1)
• Our Configuration:
Processor: Xeon E5630, 2.53GHz, 4 Cores
Memory: 96 GB
Storage:
Two Mirrored Spinning Disks For OS / Binaries
Three Striped 480GB Solid State Drives
(Providing 1.3 TB Local DB Storage)
• Peer to Peer Ring
• Hot Swappable - Fault Tolerant
• "What's Your Insurance Company?"

18. Why DataStax Cassandra?
• A Certified, Production Ready Version Of Cassandra
• 24/7 World Class Support
• Integration With Hadoop
• Integration With Solr
• OpsCenter (Multi-Data Center Management Tool)

19. • Doc Store and UI
• Load: 3x Anticipated Load
• Total Time Of Run: 1.75 hours
• Max Document Size: 10k (25k, 50k and 75k DS)
Results
Average Response Time: < 300ms
Maximum Running Vusers: 684
Total Throughput (bytes): 7,176,727,121
Average Throughput (bytes/sec): 1,993,535
Total Hits: 342,833
Average Hits per Second: 95
DB Server CPU < 0.3%
Performance

20. • Document Store only
• Load: 100x Anticipated Load
• Total Time Of Run: 1 hour
• Document Size: 25k, 50k and 75k
Results
Average Response Time: < 100ms
Maximum Running Vusers: 2,200
Total Throughput (bytes): 2,291,522,553
Average Throughput (bytes/sec): 565,808
Total Hits: 834,640
Average Hits per Second: 206
DB Server CPU < 1%
Performance

21. Wrapping It Up

22. Cloud Decision Points
• Cost Savings
• Continuous Availability
• Performance / Dynamic (Elastic) Scalability
• Global Distribution Of Access Points
• Redundancy
• Disaster Recovery
• Resiliency To Node / Connectivity Loses A Must

23. • Think About Reporting Up Front
• Data Analytics – Hadoop and Solr Are Heavy Duty
• More Expensive Hardware?
• Different RAID Configuration (Not Striping)
• Get Training – Especially About Schema Design
What Would We Do Differently?

24. Consider The Human Element...
• Mind Shift For RDBMS Folks
• Need To “Let Go” That Data Needs To Be Normalized
• Experience Of Operations Team
• Netflix - 4 People Managing 800+ Nodes
Global Enterprise
• Global Presence
• Disaster Recovery
• Internet Scale
Final Thoughts...

25. Writing Space
and the
Cassandra NoSQL DBMS
Thank you!
Questions?
Brian.King@Pearson.com