To upgrade esxi 4.1 to 5.1(with vm and vmfs) in a cluster on vc 5.1

I have prepared new vc 5.1 and configured new cluster using 8 esxi 4.1 host, multiple vms are running on these 8 host, and showing utilization till 80%..have few concerns..

1.Please advice best approach to upgrade host one by one to avoid any failure/outage for  my running prod environment ?

2.And also confirm how vmware tools and hardware version should be upgraded for different vms-after host upgrade with min downtime ?

3.In case any failure during host upgrade,is there any back out plan we can preserver before upgrading host?

4.Can we go for vmfs upgrade after upgrading complete cluster [all host in cluster] or have to upgrade vms first with updated h/w version/vmware tools ?

5.Is it require to upgrade all host first(in cluster/datacenter/vc) which are connected to specific datastore before we go for vmfs upgrade?
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coolsport00Connect With a Mentor Commented:
I have provided step-by-step in previous EE posts (e.g. here:

This is what I recommend:

Procedures I do with small deployment:
1. Upgrade vCenter - you can do a new deployment or create a new VM and just redeploy vCtr and connect to a newly created DB on a supported remote DB server
2. Recreate your vCenter structure if new and install your vCenter/Host 5.x licenses (you've already done this)
3. Migrate VMs off an ESXi Host to others in your Cluster, assuming you have vMotion
4. Document your Host settings (networks, mgmt IPs, VLANS, NTP settings, etc.)
5. **THIS IS JUST PRECAUTIONARY - assuming your Hosts are using Shared Storage, I disconnect my Fibre cables to the Host
6. Use a USB or SD to connect to your Host and install your ESXi 5.x version onto this device. If you have an internal SD, you can create a bootable USB or CD and install it on your SD. You can install on local HD as well, but I just recommend SD
7. Once the install completes, log into your Host directly and configure (at this point, if you didn't already install it, you'll need to install an upgrade version of the vSphere Client)
8. Once config'd, add your Host to vCenter and migrate some VMs back to it if you like
9. Repeat for remaining Hosts
10. Once all Hosts are done, upgrade VMware Tools on your VMs (you can do groups of VMs by using the Virtual Machines tab of your Cluster)
11. Upgrade VM Virtual Hardware after Tools upgrade; NOTE: do NOT do this before VMware Tools upgrade
12. NOTE - I recommend also upgrading your Datastores to VMFS5. I also recommend doing a 'fresh' upgrade so as not to have residual VMFS3 on them. Just remove VMs off your Datastore using Storage VMotion, remove the datastore (****AGAIN, DO THIS ONLY IF ALL DATA, VMs, ISOs, ETC ARE OFF YOUR DATASTORE), then simply re-add the datastore. Now, you can do a non-disruptive upgrade to VMFS5 with VMs, etc still on your Datsatore, but you still have residual MBR until a certain point

Also, Derek Seaman goes through the process of upgrading to 5.1 on his blog site. GREAT process! (he goes through each component)


1. Test the upgrade and become familiar with it in a test environment. Move the VMs to other hosts with vMotion. Apply the upgrade to the host using the CDROM or the virtual media (remotely) if supported by the server. Check if hardware is supported. Read the Upgrade doc and release notes. Consider disabling HA during any scheduled maintenance. -IMportant: install critical patches after the upgrade.
2. Until the hosts are in 5.1, you still need to reboot after installation of VMtools.
3. If the upgrade fails, it might better to do a fresh install. If you moved the VMs to other hosts before the upgrade, it shouldn't be a big deal to install ESXi from scratch. Otherwise, the only product I know of to backup the host's configuration is Acronis vmProtect9.
4. No, don't upgrade vmfs until all other host are in 5.1.
5. yes.
patronAuthor Commented:

We are done with Test Plan.

just to confirm whether we need to pull out the host form Prod Cluster before we go for upgrade ? or just to put in maintenance  mode?

Please advice best approach  to avoid any outage..

3. is it ok if we preserve host profile before upgrading host form 4.1 to 5.1 Or can we apply that after upgrade or in case any failure ?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Put the Host into maintenance mode.

Host Profiles will not be compatible from 4.1 to 5.1.
patronAuthor Commented:
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