vSAN capacity utilization alarm 'Storage space'

Products

• VMware vSAN 7.x
• VMware vSAN 8.x
• VMware vSAN 6.x

Issue/Introduction

Symptoms:

• Alarm 'vSAN capacity utilization alarm Storage space'' is flagged in vSphere Client > vSAN cluster > Summary.
  
  
  
  
  
• This behaviour is seen in spite of no new VMs been added in the vSAN cluster. 
  
  
• Total storage usage is > 80%.

Environment

VMware vSAN 

Cause

• High number of snapshots on VMs / templates takes up more space than expected.
  
  
• vSAN Storage space has exceeded the warning threshold of 80%:
  
  
  
  
  
• RAID-1 storage policy used by the VMs on the vSAN cluster further amplifies the used space.

Resolution

1. Remove old snapshots on the VMs running on the vSAN Cluster
   (Avoid long chain of snapshots as it occupies huge space on vSAN datastore).
   
   
2. Remove any unused or redundant VMs if found on this vSAN Cluster.
   
   
3. If above mentioned measures do not free up any substantial space on vSAN datastore, consider to add additional disks to existing vSAN data nodes.
   
   
4. If adding more disks is not feasible, add more ESXi nodes to the vSAN cluster to increase overall storage capacity.