vCenter Server Linked Mode or not?

[jzwerger]

Hi,

i have got the following scenario: I have an existing Esx Environment with 8 physical ESX hosts and 1 virtualized vCenter server for the entire Management and 1 Cluster. Now (for Oracle licensing costs) my company advised me to create a second Esx Cluster with 4 physical ESX hosts.

My question is related to the vCenter for the Management of the two Clusters. It's best practice to install a second vCenter Server for the Oracle VM Cluster and link the two vCenter servers together (Linked Mode) or to let them operate separate or to only use 1 vCenter Server for the managament of the 2 Clusters?

What in your opinion are the PROS and CONS?

thanks!

[Abhilash Basavarajaiah]

I would say use just one vCenter.

Lets start with PROS of using 1 vCenter

vCenter can support all the hosts and its not a big number.

You will save on a vCenter and a windows license.

Lesser complexity.

CONS of using 2 vcenters

Management complexity increases.

Up gradation and other things get complicated.

A single vCenter can easily support 8 hosts. I have seen people using linked mode only when there are two sites.

[jzwerger]

Thanks for your reply!

I forgot to mention that the physical ESX-Hosts are sparsed over 2 sites. So it's better using Linked mode also for "Disaster" cases? Because SSO-DB gets replicated in a Linked Mode, right?

Thanks

[Abhilash Basavarajaiah]

How is the network connectivity between sites? If its good a good connection i would still suggest you to consider putting a single vCenter and managing the hosts centrally.

You could install SSO in multi site mode which will give failover capabilities for SSO across sites.

Read more about it here

VMware vSphere 5.1

[mahantesh_dinda]

If it is a good network connection, a single vCenter can do as there are not many ESX servers to manage.

Else, you can use two vCenter Servers one in each site having their own SSO installed in multi-site mode.

PRO's:

1. Speed will be better

2. This setup can scale up to add more hosts in future if there are such prospects.

3. SSO in multi-site helps have the replication of all users and groups and in case of disaster, a new SSO can be installed in multi-site mode connecting to other SO and replicate the users/groups.

[jzwerger]

The connection between the two sites is a 4G fiber connection. It's sure that in future the number of physical ESX hosts will increase, but not excessive (planned 10 hosts in one cluster and 6 in the other). I know now that using 2 vCenter Servers in Linked Mode, my environment is getting more complex, but if I use one single vCenter Server I do not have a disaster solution, using two vCenter Servers I have one, right?

[Abhilash Basavarajaiah]

When you say disaster and two vCenters. Are you using any DR solutions like vCenter SRM or any array replication solutions? Because connecting vCenters in linked mode will not just give you DR solution.

[jzwerger]

Yes, from the point of Storage Array, we have 3PAR F400 Storages with Peer Persistence, so the storage has the capability to do a seamless failover for VMware, without interruption. So using linked mode will give me a DR solution for the vCenter Server?

[Abhilash Basavarajaiah]

Just Linked mode will not give you DR solution. Linked mode is used when there are two vcenters and they are linked together to achieve a centralized management. It will show all you Inventory in both the vCenters. The First vcenter will have both its and 2nd vCenters inventory and the Second will have its own and 1st's inventory.

But by using a multi-site SSO the users/permissions will be replicated, and since you have array replication, both of them should work together and give you DR.

[jzwerger]

Ok, then I think linked mode will be the solution for me.

Thank you!