Help with vCenter fresh install and failover-cluster

[robin_grandin]

Hi All,

This will be my first post but I need some help. Im fairly familiar with VmWare and we use it in a small business environment.

I'm having trouble finding any decent instructions of how to setup a VmWare failover-cluster.

We have 2 identical ESXi hosts and run all our VM's on one of it. Now we want to improve availibility by using the 2nd ESXi host as a failover - should the primary one go down.

I've labbed around a bit and found it was very easy to setup a real cluster to make the ESXi's share resources and run the VM's from our SAN.

What are the requirements to setup a failover beween primary and secondary esxi?

(doesn't have to be a complete step-by-step but some points would be gladly apreciated)

Is it better to make a cluster of them with a shared resource pool?

Can this be setup while ESXi's are Live and powered on?

[robin_grandin]

Nobody that can give me any guidelines to this?

[admin]

Welcome to the community Robin. But I'm sorry that nobody gave a try to help you out, may be you posted at a wrong time. Or consider changing this posted in https://communities.vmware.com/community/vmtn/availability

What are the requirements to setup a failover beween primary and secondary esxi?

(doesn't have to be a complete step-by-step but some points would be gladly apreciated)

You haven't mentioned the ESXi versions here. So I'm giving you here the link documentation link which will help you to setup the vSphere HA cluster, which is nothing but what you have mentioned as Failover cluster.: vSphere Documentation Center

Is it better to make a cluster of them with a shared resource pool?

When you say resource pool, it has altogether a different meaning in the context of vSphere . Though the answer to your question is , the cluster taken as a whole will have the resource from the ESXi hosts clustered together.
But considering a single VM, it wont be sharing the resources from multiple ESXi hosts.

Can this be setup while ESXi's are Live and powered on?

As you have identical ESXi machines, I would say it is very much possible. But I doubt the availability of VMs.

~dGeorgey

[admin]

What are the requirements to setup a failover beween primary and secondary esxi?

The checklist / requirements needed for high availability.. vSphere Documentation Center

~dGeorgey

[robin_grandin]

Hi Georgey,

Thanks for your time.

I'm running ESXi 5.5 on both hosts.

They're not on identical hardware, they're from different generations.

However what i would like to achieve is that these two hosts will be "clustered" so that if one of the ESXi's goes down the VM's will still continue to run....

At same speed if resources are available...or if possible, slower when one host goes down.

Basically a small failover (not a switchover...because i want to be able to use the resources available).

So what's your advice for this scenario?

I have been labing around  with vCenter server (and i utterly hate the stupid flash version for 5.5 it's broken by design ) and seen all the options available it's just.....where to start to make it as good as possible so that I can afford that one hosts goes down or into maintenance mode and still leave all VM's powered on.

I did mess with the settings for the cluster but no matter how i put it i got an error message that said that "you dont have enough available resources" or something like that...when i tried to poweron a VM in the resource pool. (yet i had both Cpu's, cores, memory and storage available). Disabling the settings on the cluster made the VM able to power on.

Thanks in advance.

[admin]

Basically a small failover (not a switchover...because i want to be able to use the resources available).

If you can not afford downtime for VMs then Fault Tolerance is the best option. But it has got its own limitations like no support for SMP VMs. [VMware KB: VMware Fault Tolerance FAQ ]

So what's your advice for this scenario?

> A 3 ESXi node cluster.

> Enable HA, DRS, DPM

> Keep FT enabled for the VMs which can not afford downtime.

where to start to make it as good as possible so that I can afford that one hosts goes down or into maintenance mode and still leave all VM's powered on

Its good to have 3 ESXi hosts in a cluster. There is a very good read on HA before you jump in.. http://www.yellow-bricks.com/vmware-high-availability-deepdiv/

What you do is;

> Make sure you have servers which can be configured with HA.

> create a cluster.

> Add your ESXi hosts into cluster.

> Enable HA, DRS, and DPM. [Make sure you meet all the pre requisites (mainly network & storage) for vMotion.]

I did mess with the settings for the cluster but no matter how i put it i got an error message that said that "you dont have enough available resources" or something like that...when i tried to poweron a VM in the resource pool. (yet i had both Cpu's, cores, memory and storage available). Disabling the settings on the cluster made the VM able to power on.

vSphere "Admission control"  is causing the problem here. Only Disable  Admission control, you would be able to power on the VM.

~dGeorgey

[robin_grandin]

Hi Georgey,

Thanks again.

Let's see if i have understood it correctly.

So it's not recommended to so this with 2 ESXi hosts only? Why do you recommend 3?

...the way i was thinking is that as long as they're both identical CPU and Memory and as long as you keep enough Resources available in the pool (like not going over 50% of either memory or cpu) i got the impression that it should work with 2 hosts.....or am I missing something?

For servers to be able to support HA- which license is required for that?

It's a jungle and not very good presented by VmWare if you ask me. Is for instance, for a small business such as us, the "vmware Essentials kit" enough?

What's the benefit of making a "switchover" instead of a resource-pool with fault-tolerance enabled?

....i am kinda exploring the alternative as well since currently all VM's we have can be run on a single host but it would be nice to configure it so if the hosts-fail the VM's will still run off Another host.

[admin]

So it's not recommended to so this with 2 ESXi hosts only? Why do you recommend 3?

There's nothing wrong in using a 2 Node cluster but  smaller-sized clusters require a larger relative percentage of the available cluster resources to be set aside as reserve capacity to handle failures adequately.

For example, to ensure that a cluster of three nodes can tolerate a single host failure, about 33 percent of the cluster resources are reserved for fail over whereas a 2-node cluster requires 50 percent be reserved.

as long as you keep enough Resources available in the pool (like not going over 50% of either memory or cpu) i got the impression that it should work with 2 hosts.....or am I missing something?

You are right on your point.

For servers to be able to support HA- which license is required for that?

For 3 servers with 2 processors each Essentials Plus would be enough to avail HA.

What's the benefit of making a "switchover" instead of a resource-pool with fault-tolerance enabled?

By the term switch-over I persume that you meant vSphere HA.
>> I would like to add a point here. To Enable FT on a virtual machine, that needs to be running in a host which is part of HA enabled cluster.

HA restarts your VM on another host if there is a host failure, and FT doesn't make any service interruption and the VM will be available even if there is a host failure.

~dGeorgey

[admin]

So it's not recommended to so this with 2 ESXi hosts only? Why do you recommend 3?

Note that when you  to perform an upgrade of one of the ESXi in a 2 node cluster you will be running temporarily without protection for your VMs', meaning all your VMs will be moved onto a single host runs without a fail-over host.
Hence recommended to go with 3 as the minimum. Nevertheless, two works fine.

~dGeorgey