Usefulness of Amazon ELB (Elastic Load Balancing

Question

We're considering to implement an ELB in our production Amazon environment. It seems it will require that production server instances be synched by a nightly script. Also, there is a Solr search engine which will need to replicated and maintained for each paired server. There's also the issue of debugging - which server is it going to? If there's a crash, do you have to search both logs? If a production app isn't behaving, how do you isolate which one is is, or do you just deploy debugging code to both instances?

We aren't having issues with response time or server load. This seems like added complexity in exchange for a limited upside. It seems like it may be overkill to me. Thoughts?

Answer 1

You're enumerating the problems that arise when you need high availability :)

You need to consider how critical is the availability of the service and take that into account when defining what is the right solution or just over-engineering :)

Solutions to some caveats:

• To avoid nightly syncs: Use an EC2 with NFS server and mount share in both EC2 instances. (Or use Amazon EFS when it's available)
• Debugging problem: You can configure the EC2 instances behind the ELB to have public IPs, limited in the Security Groups just to the PCs of the developers, and when debugging point your /etc/hosts (or Windows equivalent) to one particular server.
• Logs: store the logs in S3 (or in the NFS server commented above)