Github user zhan849 commented on a diff in the pull request:
https://github.com/apache/helix/pull/266#discussion_r227597163
--- Diff: designs/aggregated-cluster-view/design.md ---
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+Aggregated Cluster View Design
+==============================
+
+## Introduction
+Currently Helix organize information by cluster - clusters are autonomous
entities that holds resource / node information.
+In real practice, a helix client might need to access aggregated
information of helix clusters from different data center regions for management
or coordination purpose.
+This design proposes a service in Helix ecosystem for clients to retrieve
cross-datacenter information in a more efficient way.
+
+
+## Problem Statement
+We identified a couple of use cases for accessing cross datacenter
information. [Ambry](https://github.com/linkedin/ambry) is one of them.
--- End diff --
Sure (will also update design doc about it).
Ambry uses Helix spectator in both their router (for retrying get requests
remotely if failed locally) and storage node (for data replication purpose).
Given the amount of clients that need global information, it would be more
cost-effective for them if aggregated information are provided locally.
---
