Running Old and New Vcenters at the same time on same San

[HMorris]

We are moving from VSphere 4.1  to 5.5. We are very small with only 3 hosts running about 20 guest VM's on a SAN.  Our old VCenter VM is still on Win 2003 and I am changing this  as well.

So rather than doing an upgrade from 4.1 to 5.5 and converting the older vcenter 4.1, we decided to just complete a brand new installation of VSphere 5.5 to a new server we have.  We also installed a brand new Vcenter 5.5 Appliance as well. So essentially we have two different installs of Vcenter, old and new running.  Then we plan to manually move the existing esxi 4.1  hosts into the new Vcenter appliance.   Then eventually move over the guests from an existing host to the new box and then wipe and reload each older host with 5.5

So I have already completed the first half of this project.  But  I have a question.

During the changeover from Windows VCenter 4.1 to the new esx host and VCenter appliance 5.5. I will be running both VCenter's (ver 4.1 and ver 5.5) simultaneously for a short period of a few days.  One still running on the older 4.1 host and the new vcenter 5.5 running on the brand new esx 5.5 host.

We will walk one host at a time  from the old VCenter and it will be added to the new Vcenter 5.5 appliance.  But I will be sharing my only SAN of course. If I am doing this and running  both versions of VCenter (old and new) at the same time and sharing my same SAN datastores at the same time,  is there any problems with doing this?  I didn't think so but I am not sure.

I installed the first new esxi host and I have pointed to my SAN datastores with no problems. And the datastores appeared as they should.  But when I add this new host to the new VCenter,  as part of the setup process it displays all the relevant San datastores.  I thought this was odd to show during the VCenter “Add a host” step.  Are there any restrictions to running two different VCenter VERSIONS at the same time on the same datastores  ?  

Thank you.

HMorris

[Sateesh_vCloud]

Welcome to the community HMorris

I can understand most of the scenario but little more information is missing.

Site 1

vCenter 4.1

3 ESX hosts

20 VM's

Data stores - A,B & C (as example)  - Assuming you have FC SAN box

Site 2

vCenter 5.5

3 ESXi hosts - brand new

Data stores - A,B & C or any extra LUNs?  - Assuming you have FC SAN box

As mentioned above :   If you are mapping same LUNs with new Site 2 and doing the installation of ESXi on local disk - there is no problem.

Tickey part is how you migrate the VM's.

Perform the Site 2 Installation completely. Move the ESX 4.1 Servers to new vCenter - Add them in same cluster of brand new servers - Shared the Data stores A,B & C with new servers - Perform Storage Migration of VM's also V-Motion to new hosts.

No common IP's are used between two sites to reduce the complexity

[a_p_ · Accepted solution]

You can have multiple vCenter Server instances running in the same environment. What you need to take care of is that the ESXi  hosts which share the same datastores do not access each other's VMs (i.e. don't add the VMs to multiple hosts). Also keep in mind that only VMFS3 datastores can be accessed by both versions, so don't upgrade the VMFS datastore to VMFS5 while still running the v4.1 hosts.

>>> as part of the setup process it displays all the relevant San datastores

That's ok. When you add a host to vCenter Server it will show all connected datastores as well as the VMs which are registered on this host.

André

[mevm83]

Hi,

It seems that to migrate vms to new server we have to first remove all host from old cluster and add them new one right? Because to migrate storage and vms, to new hosts they have to access old datastores too (vmfs 3 datastores).

So let say we didn't do so, Site 1 has cluster 1 with 2 old hosts and a,b,c datastores (vmfs 3), Site 2 has cluster 2 with old host and new host. If we give access datastores a,b and c to new hosts, will there be conflict? I mean will there be any conflict if DataStore used by two cluster hosts  simultaneously?