[GitHub] [trafficcontrol] rawlinp commented on issue #6902: Delivery Service and Traffic Router can't loadbalance traffic between cache servers

[GitBox <gi...@apache.org>]

rawlinp commented on issue #6902:
URL: https://github.com/apache/trafficcontrol/issues/6902#issuecomment-1157761003

   This is not a bug. Traffic Router is not a load balancer -- it is a content router. If requests were simply routed to servers in a round-robin fashion, cache hit ratio would be terrible, because nearly every request for a piece of content would be made to a cold cache. For example, if you have 100 edge caches and TR round-robined requests to all of them in turn, the first 100 requests for a given piece of content would be cache misses. The CDN is designed to cache content as efficiently as possible, which is why it uses a concept known as Consistent Hashing (as opposed to round robin).
   
   That said, if using HTTP-routed delivery services, you could in theory set your initial dispersion to 100. But that would mean every unique piece of content would be duplicated 100 times in each of your cachegroups. If the amount of storage is not enough to handle that amount of duplication, your caches will quickly "wrap around" and content will be constantly getting pushed out of cache, reducing cache efficiency. Plus, the first 100ish requests for that given piece of content would be cache misses altogether.


-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: issues-unsubscribe@trafficcontrol.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org