Have you experienced a Moodle site failure during a critical time? Are you worried that your Moodle service won't be able to meet your needs at the busiest times? This session will cover a variety of methods to ensure optimal performance of Moodle under peak load. The session will address general resource guidelines for expected concurrency and help administrators determine the correct sizing of IT resources for an expected Moodle load. The session will also cover benchmarking techniques that can be used to measure the actual performance of your Moodle infrastructure.

1. Moodle Performance and
Scalability Assurance
Jonathan Moore

2. Analysing Usage
● We size for the highest peak
● Describe the peak scenario
● How many users?
● How short of interval?
● What are they doing?
● How much growth is expected?

3. The mdl_log
● A wealth of information
● Many sites have > year of data
● Determine concurrency
● Determine % of activity types
● Visualize historical usage

4. Optimizing Performance
● Use a PHP accelerator
● Balance your memory budget
● Make InnoDB buffer pool same size as DB (see
mysqltuner.pl)
● Most sensitive to slow disks
– Sessions
– Moodle source
– Moodle database

5. Some General Sizing Guidelines
● ~25-30 MB per apache client /w accelerator
● ~125-150 logged in users per core
● ~4-6 x more resources for a user's first minute
● ~5 logged in users supportable per apache
child
● DB generally 1/10 size of Moodledata folder
● 5-10% of population is common peak for
concurrency

6. JMeter Benchmarking
● Simulates simultaneous user activity
● Gathers response and throughput results
● Not a browser can't test javascript
● Can use to measure +/- of changes
● Can use to estimate expected concurrency, but
harder

7. What to Use for Testing?
● Copy of production for test site
– +Harder for server to cache
– -More likely errors in results due to broken content
– -Have to reset user passwords
● Synthetic test site
– +Can use known good content less false errors
– -Takes a lot of time and effort to prepare
– -Smaller DB = easier server caching
● Hybrids

8. Testing Changes
– Single test user and course may work well
– More accurate the test rig less likely to miss
problem
– Run same test between changes
– If results degrade don't move forward with change
without careful review

9. Measuring Concurrent Capacity
● Test users, enrolment, and course population
should be on par with production site
● Test set mix should reflect activity % of
production site
● Calculate
– Simultaneous logged in user count
– Simultaneous logging in users count
– They are different
– Know what you need for each

10. Moodle 2.6 and JMeter
● New integration available
● Creates test plan with many activity types
● Provides comparison reports
● Only single user / single course test?

11. Tools
● jMeter
● SQL queries + mdl_log
● PHP Accelerator
● Cacti, munin, nagios, etc
● CLI: top, sar, innotop, mysqltuner.pl etc

12. Questions?
● jonathan@elearningconsultancy.com
● Twitter: @moorejon
● Skype: moorejon07