Re: Guide for upgrading Vsphere 4.1 to 5.5?

Hi Friend,

- Upgrade your vCenter to 5.5 or install a new one so you can manage your ESX 4.1 hosts
- Use the update manager to upgrade your first host 4.1 to 5.5
- Attach the  all other 4.1 and newly upgraded 5.5 ESX to the vCenter
- Ensure the external Storage is visible to both 4.1 and 5.5
- Migrate your VMs from other 4.1 host to new 5.5 host with Storage VMotion
- Upgrade VMware tools on the VMs

Refer:http://pubs.vmware.com/vsphere-55/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-55-upgrade-guide.pdf

https://kensiltra.wordpress.com/2013/10/18/upgrade-vsphere-4-1-to-5-5/