2. Business requirements
• Check your requirements!
• Recovery Time Objective (RTO)
• Recovery Point Objective (RPO)
• Budget
• SLA from your providers
4. Cloud or my own?
• Cloud is more flexible and more scalable on demand
• Easy grow with the cloud
• Own hardware might cost less
• Choose your provider wisely (read the fine prints!)
• Snapshots!
5. Simple setup
• One Web server + one or more app servers + one db server
• Pros:
• Cost is not too high
• Scales your WO applications
• Cons:
• No high availability for your Web and database services
6. HA for databases
• Replication/standby
• Only failover, or read-only slaves
• Great for multi locations
• Clustering/load balancing
• Might have some drawbacks
• Not ideal for multi locations
• Amazon RDS
10. Heartbeat
• Can mounts a virtual network interface
• Monitor services and switch over
• Failover or load balancing
11. HAProxy
• Load balancer as software
• Can use Heartbeat for LB failover
• Can look for session ID in cookie or url path
• Can act as basic firewall
• Not only for HTTP(S)
12. DRBD
• RAID 1 over a network
• Failover or clustering, depends on file system
13. Basic HA setup
• Two Web/apps servers with Heartbeat (active/passive)
• Two database servers and Heartbeat and DRBD
14. Average HA setup
• Two Web servers with Heartbeat
• Two app servers with Heartbeat (for Monitor)
• Two database servers and Heartbeat and DRBD
15. Fantastic HA setup
• Two load balancers with HAProxy and Heatbeat
• Two active Web servers
• Two or more app servers
• Two database servers, with Heartbeat and DRBD
16. Tools for the cloud
• Auto scaling
• RackSpace Auto Scale
• Amazon Auto Scaling
• Load balancers
• Amazon Elastic Load Balancer
• Linode NodeBalancers
• Rackspace Cloud Load Balancers
17. Rackspace Auto Scale
• Can check by memory, CPU, load, file system and network
• Have APIs
• NeedVM images
• Specify minimum and maximum
18. Amazon Auto Scaling
• Works with Cloud Watch
• Will scale based on network requests or load
• Needs AMIs
• Have APIs
• Specify minimum and maximum
19. Amazon Elastic Load Balancer
• Supports TCP, HTTP, HTTPS and SSL
• Can check path (URL)
• Can load balance between regions
• Integration with CloudWatch
• Can use the application’s session cookie (wosid)
20. Linode Node Balancers
• Supports TCP, HTTP and HTTPS
• Session Stickiness works with tables of IPs or HTTP cookie
• Health check can do a status (2xx, 3xx) check or regex on body
21. Rackspace Cloud Load Balancers
• Can cache content (images, audio, video, css)
• Can display error page when all nodes are down
• Session persistence by cookie for http only
• Required for Auto Scale
22. Mixing
• You can use HAProxy and heartbeat in the cloud
• DRBD might work, but I can’t confirm
23. Monitoring/relaunch
• You can use Nagios’ event handlers to restart stuck instances
• Amazon Cloud Watch and Rack monitoring are good too
• Start new app instances orVMs based on memory or other
criteria
25. TODOs
• Scripts to monitor state of apps for scaling
• Event handlers for Nagios
• Replace JavaMonitor with something else
• Should we get away from wotaskd and the WO adaptor?
