Unexpected change of vmdk name and file size after volume relocation in vsan and vsan direct datastores

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

1. For the file name change part : Its happening as per design. As per the current design a disk is identified by its uuid, and uuid doesn't change after relocation. Applications should use the UUID to identify the relocated disk and not name. 

2. Incorrect disk size seen on UI whizard/mob/API where we have listing of vmdk size.  This size reported may not be equal to size of the source disk/vmdk initially. But there is no data loss issue here, only UI/mob/API interface provides a different size compared to source . 

On 7.0.3, during standalone volume migration via CNS, there is no way to provide the target disk type. In current implementation if user doesn't specify the target disk type during relocation, by default it will be created as 'THIN' disk.

Environment

VMware vCenter Server 8.0.x

Cause

When the source disk is of type LZT (during volume creation via CNS on vSANDirect, LZT is default type).  When this disk is migrated without specifying any disk type, on target it is getting created as 'THIN' and due to this size of the reported disk may get reduced. Due to this conversion size reported may be different.

Also If some data is written to the disk during migration, then we may see size differences in source and destination disk too.

Resolution

VMware is aware of this issue and will be fixed in the future release of vSphere 8.0