vSAN Cluster Configuration Consistency Error in Skyline Health after enabling compression. Issue: "Compression is disabled, but should be enabled"

Products

• VMware vSAN 7.x
• VMware vSAN 8.x

Issue/Introduction

Symptoms:

• Skyline Health indicates a "vSAN Cluster Configuration Consistency" error:

• The vSAN cluster configuration consistency error indicates issue: "Compression is disabled, but should be enabled": 

 

• When disabling/re-enabling compression, you encounter error indicating Resource check failing:

 

Environment

• vSAN 7.x
• vSAN 8.x

Cause

• There is Insufficent space on vSAN Datastore to convert the disk groups to use compression. 
• Enabling compression requires that each disk group be reformatted. 

Resolution

• Verify that all vSAN hosts are the same ESXi version & build #. See TechDocs: "Determining the build number of VMware ESX/ESXi and VMware vCenter Server.
  • NOTE: If a new vSAN node was just added and there is difference in build numbers between hosts, see instead: Skyline Health Alert -- "vSAN cluster configuration consistency" -- Deduplication & Compression is disabled but should be enabled
• Validate that all disks are the same disk format version in vSphere Client:  Cluster -> Configuration Tab -> Disk Management.  See TechDocs: Determining the Current vSAN On-Disk Format
• Disable, then re-enable compression to verify if any errors were encountered when enabling compression.  See TechDocs: Disable Deduplication and Compression on vSAN Cluster and Enable Deduplication and Compression on an Existing vSAN Cluster, then verify if any errors are encountered as it tries to convert the disk format.
• Free up vSAN Space, as indicated by error message from the "Convert disk format for vSAN cluster" task, as shown above.