anchor.diff:  
   #### <a id='resource-pools'></a> Resource Pools
   
  +To configure your resource pools according to the requirements of your deployment, see <%=vars.pools_link%>.
  +
   Configure your <%=vars.pools_link%> according to the requirements of your deployment.
   
   Each IaaS has different ways of limiting resource consumption for scaling VMs. Consult with your IaaS administrator to ensure additional VMs and related resources, like IPs and storage, will be available when scaling.
  
positive.code: 
  <strong><%= modified_date %></strong>
  
  This topic explains how to configure Cloud Foundry (CF) for high availability (HA), and how Cloud Foundry is designed to ensure high availability at multiple layers.
  
  <%= vars.ha_ert %>
  
  
  ## <a id='capacity'></a> Configuring High Availability
  
  This section describes how to configure system components to ensure high availability. You accomplish this by scaling component VMs and locating them in multiple Availability Zones (AZs), so that their redundancy and distribution minimizes downtime during ongoing operation, product updates, and platform upgrades.
  
  Scaling component VMs means changing the number of VM instances dedicated to running a functional component of the system. Scaling usually means increasing this number, while scaling down or scaling back means decreasing it.
  
  Deploying or scaling applications to at least two instances per app also helps maintain high availability. For information about scaling applications and maintaining app uptime, see the [Scaling an Application Using cf scale](../devguide/deploy-apps/cf-scale.html) and [Using Blue-Green Deployment to Reduce Downtime and Risk](../devguide/deploy-apps/blue-green.html) topics.
  
  ### <a id='azs'></a> Availability Zones
  
  
negative.code: BOSH detects if a VM is present by listening for heartbeat messages that are sent from the BOSH agent every 60 seconds. The BOSH Health Monitor listens for those heartbeats. When the Health Monitor finds that a VM is not responding, it passes an alert to the Resurrector component. If the Resurrector is enabled, it sends the IaaS a request to create a new VM instance to replace the one that failed.
  
  <%= vars.resurrector %>
  
  