Problem - Redis flushed on some stage so while sale or heavy traffic then all server CPU goes 100%.
Result - server stop responding and sites down.
Servers [ Amazon]
- 2 webserver with 32 GB Ram with 16 core processor - 1 cache server with Redis and Solr install - amezon CDN used for images - Nginx Server + phpfpm - Sticky session enabled - RDS database
Magento Application -
1 . 30,000 products 2 . 1000 categories 3 . 4 websites with mulitdomain 4 . 5 stores - one site have 2 store views heavly customized application alots of rewrite
Site load - 400 concurrent user per minute.