Multiple vCenters and Clusters

[Nathan Harwood]

Hi,

We currently have a single vCenter server (7.0.2) with 1 cluster and we are planning to add 2nd vCenter server and cluster at another site.

 

This second cluster will be for both production VMs and also for DR for the 1st site. We still haven't decided on how we will do DR but it will most likely be involving SAN to SAN replication and SRM.

 

Is it recommended to use link mode with vCenter in this situation or should we leave the two vCenter stand alone. Also in linked mode what happens if one of the vCenter servers goes down?

 

We will sometimes need the ability to migrate VMs between sites but my understanding is that this can be done with or without link mode.

 

Thanks,

Nathan

[Duncan Epping]

the advantage of linked mode would be that you could operate both environments from within a single interface. If the connection breaks between the two then that obviously won't work anymore, but other than that that should not be a problem. We support DR both with linked mode enabled and disabled. I guess migrating VMs between vCenter Server instances is easier when have linked mode enabled, but as you said it also is possible without. I guess you need to ask yourself how often these things happen, and if you feel more comfortable with fully isolated environments.

[Nathan Harwood]

Hi Depping and nachogonzalez,

 

What happens if one of the vCenter servers go down when in linked mode beside losing access to the servers connected to that vCenter? Such as will we still be able to access the other vCenter and servers connected to it.

 

Thanks,

Nathan

[nachogonzalez]

Yes, you still be able to manage the servers linked to the other vCenter.

Let's say you have Site A with one vCenter and 4 hosts and you have Site B with 4 vCenters and 4 hosts.
both running in linked mode.

If site a vCenter goes down for some reason you will still be able to manage site B.
also, if only the vCenter goes down (for example, a service fails, a partition gets full, etc) and the ESXi hosts are not affected (meaning, that you don't have a complete site A outage) you can still manage the ESXi hosts directly either from the host UI, SSH or DCUI.

Hope that works.

[Nathan Harwood]

Thanks for confirming. Looks like we will go linked mode.

 

Now just need to decide between SRM or Veeam.

[nachogonzalez]

This is just a personal opinion: I prefer Veeam B&R
I have not used SRM for a long time and in the past (i think version 5) when using array replication it used to have limitations, while if you used vSphere replication those limitations were not there.
I know SRM and vSphere replication evolved quite a few since the last time I used them so my opinion might not be the best.

[nachogonzalez]

Hi Nathan, hope you are doing fine.
Let me reply all your questions


We currently have a single vCenter server (7.0.2) with 1 cluster and we are planning to add 2nd vCenter server and cluster at another site.

 

This second cluster will be for both production VMs and also for DR for the 1st site. We still haven't decided on how we will do DR but it will most likely be involving SAN to SAN replication and SRM.

This is fine, another option worth considering is Veeam REplication. 

Is it recommended to use link mode with vCenter in this situation or should we leave the two vCenter stand alone. Also in linked mode what happens if one of the vCenter servers goes down?

I don't know the official recommendation from VMware, but using linked mode would give you the ability to manage bioth vCenters from a Single Interface. 

When a vCenter on Linked Mode goes down you will be able to manage the other, but not both at the same time.

We will sometimes need the ability to migrate VMs between sites but my understanding is that this can be done with or without link mode.

Please check the requirements for cross vCenter migration here:
Cross vCenter Migration and Clone requirements in VMware vSphere 6.x and later (2106952)

Please note that linked mode will be required.