Unable to SvMotion VM from vSAN storage

Products

• VMware vSphere ESXi

Issue/Introduction

• While trying to SvMotion a Virtual Machine from vSAN datastore to a non-vSAN datastore, it may report below error.
  
  Insufficient disk space on datastore '<destination_datastore>'.
Required space: ###########. Available space: ###########.

Environment

VMware vSAN 7.x
VMware vSAN 8.x

Cause

This is due to the Virtual machine consuming more space on the vSAN datastore than the free space on the destination datastore.

Space consumed by the Virtual machine from vSAN datastore is based on the Storage policy applied to that VM.

Storage Policy Rule	vSAN Architecture (OSA/ESA)	Number of nodes in vSAN Cluster	Space consumed from vSAN datastore
FTT=0	Both	3	1x
FTT=1 using RAID-1	Both	3	2x
FTT=1 using RAID-5	OSA	4	1.33x
FTT=1 using RAID-5	ESA	3	1.5x
FTT=1 using RAID-5	ESA	5	1.25x
FTT=2 using RAID-6	Both	6	1.5x
FTT=2 using RAID-1	Both	5	3x
FTT=3 using RAID-1	Both	7	4x

Note: If the Storage policy is configured with 'Site disaster tolerance' as 'Site mirroring - Stretched cluster', the space utilization will further increased by 2x.

Resolution

• Increase the free space on the destination datastore, to have free space more than the VM space usage.
  
  Or
  
  
• Apply a storage policy for the affected Virtual machine, which can lower the space consumption on vSAN datastore.

Additional Information

vSAN svMotion caveats/considerations