VMs having a larger used space after migrating to vSAN datastore

Products

• VMware vSAN

Issue/Introduction

Virtual machines after moving to the vSAN datastore might show used space more when compared to the non-vSAN datastore.

This larger space consumption might cause the vSAN datastore to reach its maximum space usage.

Environment

VMware vSAN 7.x
VMware vSAN 8.x

Cause

Depending upon the Storage policy selected during the Clone/Storage vMotion operation, space will be consumed from vSAN datastore.

vSAN Architecture	FTT	RAID	Placement	Space consumption	Minimum Hosts
vSAN OSA / ESA	1	1	1+1 Mirror	2x	3
vSAN OSA / ESA	2	1	1+1+1 Mirror	3x	5
vSAN OSA / ESA	3	1	1+1+1+1 Mirror	4x	7
vSAN OSA	1	5	3+1 Stripe	1.33x	4
vSAN ESA	1	5	2+1 Stripe	1.5x	3
vSAN ESA	1	5	4+1 Stripe	1.25x	6
vSAN OSA /ESA	2	6	4+2 Stripe	1.5x	6

 

If 'Datastore Default' is selected as the destination storage policy, it will select the default storage policy configured for vSAN datastore. 

Resolution

This is an expected behaviour based on the Storage policy used for Clone/Storage vMotion.

Please ensure sufficient space is available on the vSAN datastore before migrating the VMs.

Additional Information

Using vSAN Policies