[TS-3418] Second hash ring for consistently hashed parent selection

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.1.0
• Component/s: Parent Proxy
• Assignee: John Rushford
• Reporter: Leif Hedstrom
• Created: 27/Feb/15 21:05
• Updated: 04/Feb/16 18:48
• Resolved: 18/Dec/15 04:55

Description

It would be incredibly useful if we allowed for an (optional) second hash ring in the consistent hashing in parent selection. Imagine a setup where you have two set of parent proxies. A child would prefer to always use a parent <n> in ring <A> for a set of URLs, <X>. In the case of parent <n> not being available, instead of rehashing <X> to the surviving members of ring <A>, we could now hash the URLs to parent <m> in ring <B>. Upon failure there, we'd then go back and rehash on the primary ring again (<A>).

This sounds complicated, but is simple in principle. Instead of immediately rehashing content upon a parent failure, we have a backup pool (potentially remote) of parents, that are likely to have the content. The idea is to minimize origin server traffic at all cost.

Issue Links

• is duplicated by: TS-2836 TS attempt to connect to dead server at least once