Having consistent LUN IDs for volumes in ESXi has historically been a gotcha–though over time this requirement went away.
- 2012 https://cormachogan.com/2012/09/26/do-rdms-still-rely-on-lun-id/
- 2013 https://cormachogan.com/2013/12/11/vsphere-5-5-storage-enhancement-part-7-lun-idrdm-restriction-lifted/
These days, the need for consistent LUN IDs is mainly gone. The lingering use case for this is Microsoft Clustering and how persistent SCSI reservations are handled. The below KB doesn’t mention 6.5, but I believe it to still be relevant to 6.5: