VMware vSphere 6.5 – HA and DRS Improvements

There is some more information about other vSphere 6.5 enhancements as below;

vSphere HA Admission Control

  • Simplified configuration workflow
  • Choose Failure To Tolerate (FTT) and we do the rest
  1. Based on % of resources reserved admission control policy
  2. Automatic calculations
  3. Overrides possible
  • Issue warning if performance degradation could result
  • Previously, HA would restart VMs, but could have caused performance impact without prior warning.


vSphere HA Restart Priorities

  • VM Restart priorities determine the order resources are allocated in the cluster post-failure.
  • Additional Restart Priorities added
  1. Highest
  2. High
  3. Medium
  4. Low
  5. Lowest
  • Additional priorities provide greater control to restart order
  • Admission Control can prevent lower priority VMs from restarting


vSphere HA Orchestrated Restart

  • Enforce VM to VM dependency chains
  1. Great for multi-tier applications that require VMs to restart in a particular order
  2. Improved application recoverability
  3. Database < App < Web
  • Validation checks
  1. Detects circular dependency rules
  2. Within and outside priority group


Proactive HA

  • Hardware OEM participation required
  • Detect hardware conditions of host components by receiving alerts from hardware vendor monitoring solution
  1. Dell Openmanage
  2. HP Insight Manager
  3. Cisco UCS Manager
  • Notifications of host impacted, its current state, error causes, severity and physical remediation steps
  • vMotion VMs from partially degraded hosts
    Configurable based on type of failure


Quarantine mode

  • In server health-aware vSphere clusters
  • Quarantine mode is a new vSphere host state
  1. Any degraded host will be placed in quarantine mode
  • vSphere DRS will Evacuate virtual machines if
  1. No performance impact on any virtual machine in the cluster
  2. None of the business rules is disregarded
  • Avoid placing virtual machines
  • Only use this server if the virtual machine demand or any of the business rules cannot otherwise be satisfied


DRS Policies

  • Even Distribution (Peanut Butter)
  • Advanced settings exposed in the UI for simpler configuration
  1. Improved availability by avoiding too many eggs in one basket
  • Consumed Memory vs Active
  1. Default: DRS uses Active memory + 25% for load balancing
  2. Policy Active: changes the DRS advanced PercentIdleVMInMemDemand=100
  • CPU over-commitment
  1. Prevent any single host from becoming over-committed on CPU
  2. Great for VDI environments


Network Aware DRS

  • Adds network bandwidth considerations by calculating host network saturation (Tx & Rx of connected physical uplinks)
  • Avoids a over-subscribing a host network links, although not guaranteed.  Best effort approach. CPU & MEM performance is still priorities over network.


  • Managed using a policy via Storage Policy Based Management (SPBM)
  • Storage IO limits are enforced using IO Filters (VAIO)


One comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s