Configuring HA help

[nizuwizu]

Hello,I'm relatively new to VMware but hoping that someone can help me or point me in the right direction for the information i need to assist with configuring HA for selected VMs.

In our current setup we have two relatively small VMware hosts that are mainly using local storage for the VMs. These two hosts are on the same LAN but in different comms rooms seperated by a dark fibre link.

We have recently added a vCenter server with the intention to use vMotion to move servers between the two hosts and vSphere replication for the more important VMs. But we understand that to do this the vCenter server has to always be available.

To overcome this we have connected the two VMware hosts to some SAN storage via FC that we have available in each of the comms rooms and presented this as storage to the two hosts. So for example in Comms room A we have VM Host A connected to SAN A and in Comms room B we have VM Host B connected to SAN B. The vCenter server VM is currently hosted on VM Host A & SAN A. This VM is replicated to SAN B at the hardware level by the SAN. Whilst SAN B is attached to Host B the vCenter VM data will only be read only until we tell the SAN controller what is the primary data. Does vSphere interact with the SAN to do this automatically and where is this configured? Is this part of the HA configuration?

Basically we want to use this small amount of SAN storage to keep our vCenter server always available if we were to lose one of the Hosts or one of the Comms rooms. Is this something that someone has configured and could point me in the right direction?

I have added the two hosts into a vCenter cluster (although i haven't enabled DRS or HA yet) but we only want to selectively keep the vCenter server VM as the only VM that is using HA for the time being. Is this possible and how?

We are using vSphere 5.1 U1 and vCenter Server 5.5.

Thanks a lot for any help.

[weinstein5]

Welcome to the Community - To answer your direct question - you can identify which VMs are protected in an HA cluster so you will be able have the vCenter VM as the only VM that will be recovered if the host fails -

The problem with set up is HA requires that all the ESXi hosts in the HA cluster see common VMFS data stores where the vCenter VM needs to be stored - This also holds true for standard vMotion where you are moving a running VM between ESXi hosts - the VM needs to be on common storage - you should be able to utilize Storage vMotion..

[Linjo]

It does sounds like Site Recovery Manager could be interesting, it does require some extra licenses but it will do a lot of the heavy lifting with the automation of the failover.

// Linjo

[nizuwizu]

Thanks very much for welcome and response.

Ok great i would have thought that would have been the case that we could identify individual VMs for HA protection. Although when i looked at the options for enabling HA on the cluster i couldn't see any obvious settings for this. I will need to relook at this. I need to be careful to only implement HA for this particular VM and not the other VMs that are on the two clustered hosts.

If HA requires that all the ESXi hosts in the HA cluster see common VMFS data stores how does this work with a hardware replicated SAN where the secodary or passive host (HOST B) is connected to the hardware replicated read-only vmfs SAN storage (SAN B). Should we be not using the hardware replication that we have available with the SANs controllers between SAN A & B and in fact using Storage vMotion? I just thought logically that the hardware replication would be best.

Would Storage vMotion work without the need for the SAN storage and in fact move the vCenter VM automatically from Host A local storage to Host B local storage?

I have already used normal vMotion to manually move a number of VMs hosted on Host A local storage to be hosted on Host B local storage. This worked very well and there was obviously no need for common storage in these examples. I'm assuming that the hosts local storage wouldn't be considered as common storage.

Thanks again, any help is very much appreciated.

[weinstein5]

High Availability solution designed not so much for a catastrophic occurrence such as losing a data center or your whole SAN - which both are possible in the realm of probability but not as likely as losing a host - so HA is designed to recover from things like a host failure or even a VM failing. For the bigger disasters you would want to look at SIte Recovery Manager as Linjo suggested -

I have already used normal vMotion to manually move a number of VMs hosted on Host A local storage to be hosted on Host B local storage. This worked very well and there was obviously no need for common storage in these examples. I'm assuming that the hosts local storage wouldn't be considered as common storage.

What you are describing is storage vmotion -vmotion by itself is only the VM changes hosts - storage vmotion is where you are moving the VM to a new host and moving the corresponding files that make up the VM with the virtual machine powered on. vmotion is an intiated process - either done automatically via DRS or DPM or manually initiated. vmotion also requires functioning hosts on either end of the transfer and a functioning vcenter. So vmotion will not work to reover if the site hosting your vcenter is down because vcenter will be offline as will the ESXi host.

Another option possibly to consider if you are wanting high availability for your vCenter is vCenter heartbeat possibly but they would share a common

[nizuwizu]

Thanks for the suggestions Linjo & weinstein5.

Ideally I don't want to add anymore cost to the setup by including SRM or vCenter Heartbeat.

Will we be able to use HA to protect the vCenter server without having it installed on storage that is shared between the two hosts? Or can HA only be used when hosts are sharing the same storage which would mean that if you lose this storage you lose the VMs and HA resilience?

Thanks again.

[weinstein5]

HA does require shared storage - Once again remembering that HA is designed for availability and not DR - the thought is the reliability of shared storage is going to be higher with the use of redundant controllers, power supplies and the use of RAID sets than that of a server - so yea\s if you were to lose the shared storage you would lose your vcenter but that is what SRM or another DR solution would be used for -

You might also want to look at the vSphere Storage Applicance - VMware vSphere Storage Appliance 5.5 Release Notes

[nizuwizu]

Weinstein, thanks again. I misunderstood what I could and couldn't do with HA in the environment I have set up.