vSphere Cluster with Different Versions of ESX

[obrienj123]

We are planning on upgrading our ESX hosts from ESX 4.1 to ESXi 5.1 Our preferred method of upgrading is via Update Manager. In the Update Manager 5.1 documentation it states the following:

"ESXi 4.x to ESXi 5.x UPGRADE is supported and ESX 4.1 to ESXi 5 MIGRATION is supported. Anyone know what the difference between an upgrade and a migration are? Am I going to need to completely rebuild the host or will it maintain it's settings.

Also is running different versions of ESX (ESX 4.1 and ESXi 5.1) withing the same cluster, supported? Any other considerations when running different versions within the same cluster. This will only be a temporary issue while we work to get all hosts upgrade.

Thanks.

J

[weinstein5 · Accepted solution]

Migration - Is where you are migrating from ESXi 4.x to a brand new install of ESXi 5x

Upgrade - is where you upgrade the existing ESXi 4.x host this will allow you to keep the host configuration      - things to keep in mind before starting is make sure the existing hardware is supported by ESXi5 - you will want to place the host to be upgraded in Maintenance mode - vCenter will have to be upgraded first

As long as vCenter is upgraded to version 5.x different versions of ESXi can coexist in a cluster

[abhilashhb]

Hi obrienj123,

If you are doing an interactive upgrade from esx 4.1 the installer wizard will offer the choice to upgrade or perform a fresh installation. If you upgrade, ESX partitions and configuration files are converted to be compatible with ESXi.

And yes you can have different versions of ESX on a cluster as far as the vCenter supports the versions and will be able to manage them. You should also make sure they are of the same processor type so it does not stop you from migrating the machines as its needed by DRS(If you are using it that is). Or you can also turn on EVC if you have servers with different processor families.

[jdptechnc]

It is perfectly valid to have different supported versions of ESXi in the same cluster managed by a version of vCenter matching the latest ESXi version.  Would I run it that way long-term?  No, but during a migration of days to weeks, I would be perfectly confortable wit it.

[obrienj123]

I am still unclear on what the "Migration" process from ESX 4.1 to ESXi 5.1 entails.

weinstein5 - you seem to think that it will be a fresh install

Abhilash H B -  you are saying that I can choose to "upgrade" and retain all my settings.

My plan for the upgrade was to upload the ESXi 5.1 image and create a baseline containing the image. Then attached the image to each host (one at a time) and remediate. I was hoping to get a better understanding of what to expect before I start the upgrade process.

Thanks again.

[obrienj123]

According to this KB an upgrade from ESX 4.1 to ESXi 5.1 is supported:  VMware KB: Methods for upgrading to ESXi 5.1

[TommyFreddy]

please have look for supports running different versions of ESX/ESXi...

Dlog: Mixing VMware ESX/ESXi Versions in a vSphere HA/DRS Cluster

[admin]

Running different versions of ESX/ESXi in an vCenter 5.0 HA/DRS cluster is supported.  Frank Denneman recently posted a good blog on this.  You may ask why would anyone want to run a mixed cluster?  Usually, this is done to facilitate rolling upgrades.  If you have a large 32-node cluster it's not practical to upgrade all 32 hosts at once, so instead you can leverage the mixed cluster support to upgrade two or three hosts at a time and "roll" the upgrade through the cluster until all 32 hosts are upgraded.

While mixed clusters are supported there are some things to watch for, specifically the VMware tools and virtual hardware versions of your VMs.  The table below provides a summary of the VMware tools and virtual hardware versions that are supported on both vSphere 4.x and 5.0.

   
From the table we can see that:

1.  VMs with virtual hardware and VMware tools version 3 are not supported on ESXi 5.0 hosts.

2.  VMs with virtual hardware version 8 are not supported on pre-5.0 hosts.

3.  VMFS-5 is not supported on pre-5.0 hosts.

With these limitations in mind, my recommendations for running mixed clusters are as follows:

1.  Verify VM virtual hardware and VMware tools versions before mixing 3.5 and 5.0 hosts in the same cluster.  VMs with VMware tools version 3 and virtual hardware version 3 are not supported on ESXi 5.0.  To avoid potential pitfalls, be sure to upgrade VM hardware versions to version 4 and VMware tools version to 3.5 before mixing  3.5 and 5.0 hosts in the same cluster.

2.  Do not upgrade virtual hardware versions while running in a mixed mode.  Once you upgrade a VMs virtual hardware version to 8, it can no longer run on a pre-5.0 ESX/ESXi hosts.  In addition, there is no option to undo the upgrade or revert back to an earlier virtual hardware version.  As such, while running a mixed cluster you should avoid upgrading the virtual hardware version of your VMs to version 8 until after all hosts have been upgraded to ESXi 5.0.

3.  Do not upgrade VMFS-3 volumes to VMFS-5 while running in mixed mode.  Wait until after all the hosts in the cluster are running ESXi 5.0 to upgrade VMFS volumes.  Upgrading to VMFS-5 will prevent any pre-5.0 hosts from accessing the filesystem.  Also, note that the upgrade to VMFS-5 is permanent, there is no way to revert an upgraded VMFS volume back to VMFS-3.

4. Do upgrade VMware Tools to the latest version.  Unlike the virtual hardware version, the newer VMware tools 5.0 version is fully supported on older ESX/ESXi 4.x hosts.   As there are many improvements included with the latest version of VMWare tools it's always a good idea to upgrade as soon as possible.  Note however, VMware Tools 4.0 is also fully supported on ESXi 5.0 so it's not required to upgrade the VMware tools right away.  If you have 3.5 hosts in your cluster you should wait until all hosts are running at ESX/ESXi 4.x or higher before upgrading VMware tools to version 5.0.

[OscarDavey]

Hi,

A migration is where you move your platform from 4.1 to a fresh install of version 5.  An upgrade allows you to upgrade the existing host along with current config.

There shouldn't be a problem running mixed versions, although you need to be careful about any new VM's created and their versions.

Yours, Oscar