Everyday Virtualization

Blog archive

Religious Issue #3: Reinstall ESXi with Hardware Installations?

In the course of an ESXi (or ESX) server's lifecycle, you may find that you need to add hardware internally to the server. Adding RAM or processors is not that big of a deal (of course you would want to run a burn-in test), but adding host bus adapters or network interface controllers comes with additional considerations.

The guiding principle is to put every controller in the same slot on each server. That way, you'll be assured that the vmhba or vmnic enumeration performs the same on each host. Here's why it's critical: If the third NIC on one host is not the same as the third NIC on another, configuration policies such as a host profile may behave unexpectedly. The same goes for storage controllers: If each vmhba is cabled to a certain storage fabric, they need to be enumerated the same.

When I've added NICs and HBAs to hosts, I've also reinstalled ESXi. Doing so, though, has its pros and cons.


  • Ensures the complete hardware inventory is enumerated on the installation the same way.
  • Cleans out any configurations that you may not want on the ESXi host.
  • Is a good opportunity to update BIOS and firmware levels on the host.
  • Reconfiguration is minimal with host profiles.


  • May require more reconfiguration of multipath policies, virtual switching configuration and any advanced options if host profiles are not in use.
  • Additional work.
  • Very low risk that the vmhba and vmnic interface enumeration is not the same as the install or the other hosts.

I've done both, but more often I've reinstalled ESXi.

What is your take on adding hardware to ESXi hosts? Reinstall or not? Share your comments here.

Posted by Rick Vanover on 11/18/2010 at 12:48 PM


Subscribe on YouTube