Reinstalling ESXi 4.1 and 5.1

[scubaed]

I have taken over a new network and the old IT guy left without supplying the root password.  I have read that the only way to recover the password is to reinstall.  It's been three years since I've touched ESX and that was version 3.  I seem to remember you can reinstall on top of what is there and it maintains your machines.  But, I could use some assistance.  I obviously do not want to wipe out the servers that are there.  Any quidance would be greatly appreciated. 

[mpanot]

I am not sure what you are refferring to version 3.

So please read on for all the option below:

1) If it's ESX 3 (Only Classic is available) : You can install ESXi4.1 or ESXi5.x (with preserve VMFS option)

2) If it's ESX 3.5 Classic : You can install ESXi4.1 or ESXi5.x (with preserve VMFS option)

3) If it's ESXi 3.5 (Visor - USB) : You can install ESXi4.1 or ESXi5.x on USB (your VMFS will be preserved as installer does not touch local disks)

4) If it's ESXi3.5 (Thin) : You can install ESXi4.1 or ESXi5.x (with preserve VMFS option)

[scubaed]

I Apologize I wasn't clear.  The machines are currently running ESXi 4.1 and the other server is running ESXi5.1.  So, I can run the reinstall and not destroy the CMFS files?

[iw123]

Just to confirm - you're not using vcenter, and the hosts are not configured to use AD authentication? Is the root account your only method available for you to log into the host ?

[vCloud9]

If you are not using vCenter/AD to manage the hosts, only option I can think of reseting the password for ESXi4/5 would be to reinstall ESXi on top of the existing install or you could also select the repair option when reinstall, which would overrite the existing ESXi system partition, and VMFS partition will be remain untouched. But you may have to re-register all the VMs once reinstallation is complete.

Also, one more article I came across which I haven't tried myself, lets you reset the password for ESXi, atleast from the user comments I see that they were able to reset the passwords for ESXi 4.1/5 as well. This option is NOT SUPPORTED by VMware, make sure you try this on your test system before you try it out on your production server.

URL to reset the password: http://vm-help.com/esx/esx3i/Reset_root_password.php