We had similar issue.
It does not stuck, it is so slow.
Do you have any RDM LUN presented to server?
If yes, you should change one flag perennially-reserved to true.
For now, you can disconnect all RDM LUNs from server, reboot and it should boot fast.
After that check KB: VMware Knowledge Base
If you don't use RDMs....I don't know
No LUNs and it is not slow. it stuck at that point.
You can use the ALT+F12 key to check the live vmkernel log. If that shows a storage issue then you need to wait until the boot process times out to load the storage
Its more likely a storage connectivity issues.
As Murali said press Alt+F12 and check the in memory logs to find out the cause for it to get stuck.
Keep us posted.
Had this same issue and the Alt-F12 to see logs explained why. The host in question was part of a previous cluster and had NFS mounts to ~20 volumes. On startup it was trying each one sequentially and after 60-90minutes it moved past the nfs41client message and finished booting.
Try upgrade first 6.5 then 6.7