Microsoft Azure Concepts – Clusters

Following on from the post Microsoft Azure Concepts – Failures, I thought it would be worthwhile creating a quick post on Azure Clusters.

  • Each Azure Cluster is made up of 20 racks
  • Within each rack is between 40 and 50 servers
  • Each server within the Azure Cluster contains the same processor generation
  • Virtual Machines within an ‘Affinity Group’ are held within the same Azure Cluster to minimise latency

Fabric Controller

  • Each rack is a fault domain
    • Each rack has a ‘top of rack’ (ToR) switch which is a single point of failure
    • Each ToR connects to the aggregation layer switch which connects all the of racks in the Azure Cluster
    • Each rack has a power distribution unit which again is a single point of failure

3 thoughts on “Microsoft Azure Concepts – Clusters

    1. The top of rack switch is a single point of failure.

      The Fabric Controller works in a cluster and you have 3 of these per 20 racks. The Fabric Controller is the Microsoft management plane and decides where to place VMs and also monitors the underlying hardware and operating systems.

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