Blog Post by Charlie Russell, Senior Product Marketing Manager
August 8, 2018
Businesses are keenly aware that they must deliver great online experiences or suffer consequences like high abandon rates and customer churn. To help accomplish their objectives, many businesses use content delivery networks (CDNs), which can deliver content found in cache within tens of milliseconds. However, when the requested content isn’t in cache, the CDN must retrieve it from origin storage where response times and performance can vary wildly.
The good news is that storage responses within tens of milliseconds are possible with origin storage that is high-performance, distributed, dynamic and well-integrated with the CDN. Here are some of the factors that determine response time and performance when retrieving from origin storage.
Multiple key factors can significantly affect response time and overall delivery for a CDN retrieving content from origin storage. One is transit path from origin storage to the CDN as well as transit within the CDN. Another is the number of locations where content is stored and how the CDN determines where to access content.
The second leg of the journey from origin to user occurs within the CDN, from the ingress PoP to the egress PoP. If the user happens to be close to the origin, the ingress and egress PoP can be the same. Otherwise, the longest part of the journey may be within the CDN. For example, suppose a user in Europe requests content that’s stored in the Americas. If the CDN has a PoP on both continents, it’s likely the CDN will ingress the content in the Americas, then haul it to Europe within the CDN for egress. The channel for that trans-Atlantic haul can vary considerably depending on the CDN.
Replication refers to placing content in different regions or even continents. However it should be noted that replication alone doesn’t improve performance, it only improves availability and durability. Regarding storage location and replication, a few typical scenarios include:
To provide performance in multiple regions, the system must intelligently retrieve from the fastest location for each user session. Scenarios include:
Why do businesses contract with CDN’s? To ensure the best performance for every user session. However cache performance is only part of the story. To complete the solution requires origin storage engineered for CDN performance, with multiple available layers of advantage to choose from. It minimizes latency from storage to the CDN edge by collocating storage and CDN edge servers. Instead of risking transit on the congested internet, a better solution transports content from origin to the user edge over a high-speed private backbone. And to dramatically improve performance and availability, it offers the option to replicate content to multiple regions and intelligently serve each session from the fastest storage location (usually the closest). Limelight Origin Storage offers all these capabilities as part of its CDN-optimized storage solution. By closing these performance gaps, response on cache miss can be improved and can even rival response on cache hit, at a cost that rivals ordinary cloud storage.