Short answer: Yes, if the vSAN datastore is truly empty. Anything still on vSAN becomes inaccessible the moment the service is turned off. In practice you must first move all VMs and files off vSAN, disable vSphere HA (the Turn Off button stays greyed out while HA is on), put vCLS into Retreat Mode, disable the vSAN performance service and remove the disk groups. Then turn off vSAN and re-enable HA so it uses the management network again.
When you would disable vSAN on a running cluster
A typical case: a cluster was built with vSAN, later all workloads moved to external NFS, iSCSI or FC storage, and vSAN is now empty but still configured. You want to turn it off to reclaim the disks, drop vSAN networking or tidy up licensing without taking the VMs down.
What the documentation says
The Turn Off vSAN page in vSAN 8 TechDocs lists “verify that the hosts are in maintenance mode” as a prerequisite and warns that all VMs and data services on the vSAN datastore become inaccessible. KB 327002 adds that vSphere HA must be disabled first and that stretched and 2-node clusters must be converted back (stretch disabled, witness removed) before you start.
Duncan Epping (VMware by Broadcom) confirmed on Yellow Bricks that disabling vSAN on a cluster with running VMs on third-party storage works without workload impact, as long as vSAN holds nothing. Because that differs from the maintenance-mode prerequisite in TechDocs, treat it as a planned change: do it in a maintenance window and have a rollback plan. If you can afford rolling maintenance mode, the documented path is the conservative choice.
Why disabling vSAN fails or the button is greyed out
KB 390679 lists the common blockers:
| Blocker | Fix |
|---|---|
| vSphere HA enabled | Disable HA temporarily (Configure > Services > vSphere Availability) |
| VMs or files still on the vSAN datastore | Storage vMotion VMs; copy ISOs, templates and content library items elsewhere |
| vCLS VMs on vSAN | Put the cluster into Retreat Mode |
| vSAN performance service stats object | Turn off the performance service |
| Disk groups still claimed | Remove the disk groups (or storage pool) from every host |
Step-by-step: turn off vSAN with VMs on other storage
- Confirm the vSAN datastore is empty: Datastore > VMs and Files should show nothing except system objects. Check content libraries, templates and ISO folders too.
- If this is a stretched or 2-node cluster, disable the stretched configuration and remove the witness.
- If you set
das.isolationaddressto an address on the vSAN network, change it back to a management-network address. - Disable vSphere HA on the cluster.
- Enable vCLS Retreat Mode so the vCLS VMs are removed from vSAN (see how to use Retreat Mode). DRS stops working while vCLS is down.
- Turn off the vSAN performance service (Configure > vSAN > Services).
- Remove the disk groups on each host (Configure > vSAN > Disk Management).
- Turn off vSAN: Configure > vSAN > Services > Turn Off vSAN, and confirm.
- Set vCLS back to System managed so the vCLS VMs are redeployed on the remaining datastores (background: introduction to vCLS).
- Re-enable vSphere HA. When vSAN is enabled, HA heartbeats use the vSAN network; after vSAN is off, re-enabling HA reconfigures it to use the management network.
After vSAN is off
- Verify HA shows all hosts healthy and datastore heartbeating uses your external datastores.
- Remove the vSAN service from the VMkernel adapters only when you no longer need them, and clean up the vSAN VLAN on the physical switches.
- The released disks can now be used as local VMFS or given to another vSAN cluster.
Further reading
- Duncan Epping: Can I disable the vSAN service if the cluster is running production workloads?
- Broadcom TechDocs: Turn Off vSAN (vSAN 8.0)
- KB 327002: Enabling or disabling a vSAN cluster
- KB 390679: Disabling vSAN services may fail on an existing vSAN cluster
