• In spite of eager-zeroed thick disk, ESXi 7.0 cannot power-on a VM with the multi-write flag.
• In hostd.log, you can see entries similar to:

2020-12-03T20:18:16.186Z verbose hostd[2099913] [Originator@6876 sub=Vigor.Vmsvc.vm:/vmfs/volumes/5d9f7395-41b8e460-b34e-f0921c02b050/MWVM/MWVM.vmx] Power On message: Cannot use non-thick disks with clustering enabled (sharedBus='physical'). The disk for 'scsi1:0' is of the type 'thin'.

• In vmware.log, you can see entries similar to:

2022-07-12T03:50:13.135Z| vmx| | I005+ Power on failure messages: Cannot use non-thick disks with clustering enabled (sharedBus='physical'). The disk for 'scsi1:3' is of the type 'thin'.

If this VMDK was inflated from thin to eager-zeroed thick disk on older versions, ESXi 7.0 might recognize this disk as "thin" format.
As a result, ESXi prevents this VM from powering on according to the limitation of multi-write flag.

VMDK inflated from Thin to Eager zeroed thick on 7.0 will not encounter this issue.

This is a known issue.

Workaround is moving this disk to another datastore with eager-zeroed thick format.

You can check this behavior by using vmkfstools.

When you run vmkfstools for flat vmdk, you can see "flags" in this result.

If this flags is "0x9", this VMDK may be recognized as "thin" format in ESXi 7.0.

# vmkfstools -D test-flat.vmdk

Lock [type 10c00001 offset 51642368 v 7, hb offset 4030464

gen 23, mode 0, owner 00000000-00000000-0000-000000000000 mtime 383964

num 0 gblnum 0 gblgen 0 gblbrk 0]

Addr <4, 17, 0>, gen 1, links 1, type reg, flags 0x9, uid 0, gid 0, mode 600

len 1073741824, nb 1024 tbz 0, cow 0, newSinceEpoch 1024, zla 3, bs 1048576