DRS is not making recommendations or migrating VMs

Products

• VMware vCenter Server

Issue/Introduction

• DRS is enabled, Fully Automated and Aggressive
• VM Distribution is set to Enforce
• In our example the vmnic0 uplink is down on one or more of the hosts in the cluster. This can be any vmnic not only vmnic0.
• Physical Switch Outage Affecting vmnic0 link state
• No DRS recommendations listed automatically or when selecting "Run DRS now" 
• DRS Migrations stop
• No DRS History reported
• Manual migration is working is expected
• DRS scores are low enough to justify a DRS migration

 

• To determine if a host has a down vmnic0 uplink: 

# esxcli network nic list

Environment

VMware vCenter Server 8.0.X

VMware vCenter Server 7.0.X

VMware vSphere ESXi 8.0.X

VMware vSphere ESXi 7.0.X

Cause

• DRS considers network bandwidth and will take in count the slowest network card in the switch
• In our case that was vmnic0 which was disconnected so bandwidth is equal to 0. Read more at Create a vSphere DRS Cluster

Resolution

1. Option 1: Restore the physical switch connectivity.
2. Option 2: Disable the failed physical vmnic uplink in the system BIOS or remove the uplink. 
3. Option 3: Remove unused vmnic completely from the switch. Select the ESXi host/Configure/Virtual_switches/vSwitch0/Manage_Physical_Adapters
4. Move vmnic in down state to Unclaimed adapters to remove it from the switch
5. After executing one of the above options, DRS should automatically migrate VMs.

 

Additional Information

Also see DRS does not automatically migrate VMs to an empty and compatible ESXi host.