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Yeah I don't get their approach. There is no way this will cause 100% delivery if one server fails within that rotation. That chances of failure go up dramatic
by korzun 12y ago
Yeah I don't get their approach. There is no way this will cause 100% delivery if one server fails within that rotation.
That chances of failure go up dramatically if 2+ hosts behind round robin fail, etc.
Not to mention once hosts resolve this to an IP they will re-use the route. This approach is not balanced.
I don't want to be /that/ guy but if they can't scale with ELB they should invest in a dedicated load balancer infrastructure that can offload requests to their cloud instances.
This is a really bizarre post.
- hatred 12y agoI am more worried about the DNS caching issue. The 2+ hosts failing should not be much of a problem if you have a separate health checker host which does nothing except gathering heart-beats from all the hosts in your fleet and updating the DNS periodically.
- korzun 12y agoThat's exactly why it's a problem. If you have 3 hosts and 2 of them go down, in this setup there is more than 50% chance that cached hosts will be trying to connect to a non-existing server. Also expecting client to perform a DNS lookup every time there is an outgoing log packet is pretty shitty for performance. You can't guarantee near instant DNS server availability for every client.
- hijinks 12y agonot to mention people that use something like a local caching daemon like nscd might cache a bad ip for a whole day
- boulos 12y agoHonestly it sounds like they just need a high performance L3 load balancer, rather than ELB. As you said though, just because AWS doesn't give them that doesn't mean the slot up was Route53 instead of say haproxy.