End of year project / Projet de fin d'année

[DylanB17]

Hello,

As I am currently in the second year of BTS SIO, I have a project for the end of the year, the more it happens the more I wonder.

Let me explain, I left on vmotion, so I have two esxi and one nas, the nas contains an NFS share and the two esxi stock their Vms on it.

The goal is to go further and make a kind of HA, automatic recovery if for example the disk is faulty or the esxi falls, so that everything automatically resumes on the other.

Each esxi contains 32GB of ram and I only have two, I saw for HA that it needed a 3rd for the witness, is it necessary?

If not, what solutions do you recommend?

Thank you in advance,

Dylan.

_______________________________________________________________________________________________________________________________________________________

Bonjour,

Etant actuellement en seconde année de BTS SIO, j'ai donc un projet de fin d'année, plus celui-ci arrive plus je me pose des questions.

Je vous explique, je suis parti sur du vmotion, j'ai donc deux esxi et un nas, le nas contient un partage NFS et les deux esxi stock leurs VM dessus.

Le but est d'allez plus loin et de faire une sorte de HA, de la reprise automatique si par exemple le disque est défectueux ou que l'esxi tombe, que tout reprenne automatiquement sur l'autre.

Chaque esxi contient 32go de ram et j'en ai que deux, j'ai vu pour de la HA qu'il fallait un 3 ème pour le témoin, est-ce nécessaire ?

Sinon quels solutions me conseillez-vous ?

Merci d'avance,

Dylan.

[Alex_Romeo]

Hi,

You must have at least two Esxi hosts and enable DRS and HA.
You need to check the resources of the Esxi hosts and make sure that if one host dies the other has enough resources to support all the virtual machines.
Hosts must be very similar in resources. Otherwise, the one with the fewest resources is taken as a reference.

ARomeo

[Alex_Romeo]

...in addition to the previous answer

vCenter HA Hardware and Software Requirements

ARomeo

[DylanB17]

Yes, it is highly recommended but with only two, does it work?

Or I can have a third machine but with only 16GB of ram.

[sjesse]

it works with two, its how I have my lab, you tend to get more errors so in production environments 3 is better.

[DylanB17]

It is only to present it during my test, it will not be put into production.

[Alex_Romeo]

Three is strongly recommended ... not mandatory. If it's just a test, present it with two Hosts and enter a note that if it were to go into production it would be better to have three hosts.

[DylanB17]

Here is my network diagram, the HA will be on the same network as vmotion, wouldn't that be a problem?

If not, do you see any inconsistencies?

[Alex_Romeo]

Hi,

Yes, "HA" on the VMotion network is fine.

The model is correct. I guess the Vlan are therefore enabled to talk to each other. The two hosts are in Cluster, maybe you should create a further box between the two hosts and write "Cluster HA".

-----

For your info:

The "DRS" features are used to balance the load between two or hosts. In your case, you would need it to better balance the load between the two hosts. However, in the event of a host failure, the load cannot be redistributed because there would be only one host.

ARomeo

[DylanB17]

During my presentation, I will clarify but the DRS loses its usefulness right?

As for the HA, if the esx falls, everything will restart well on the other side automatically?

---

For information, I have not had Vmware ESX training, so I train alone.

[Alex_Romeo]

During my visit, I will clarify but the DRS loses its usefulness right? Yes!

As for the HA, if the esx falls, everything will restart well on the other side automatically? Yes! When the host dies, HA turns off the VM and turns it on in the other host.

ARomeo

[DylanB17]

Thank you so much,

I have two other small questions:

- I must use "Vcenter server appliance" and not the "vcenter server windows" ?

- How is the replication of the Vcenter server (appliance) done? Because if the ESX or this one is installed no longer works, how does it work?

[Alex_Romeo]

Hi,

- I must use "Vcenter server appliance" and not the "vcenter server windows" ? Use Vcenter Appliance (VCSA). The Server vcenter Windows version has been deprecated, it will be gone.

- How is the replication of Vcenter server (appliance)? Because if the ESX or this one is installed, how does it work?

I have not understood this question well. You need the vCenter to hook up hosts and manage them. In the vCenter you create the Cluster and enable the HA feature.

The vCenter also has an interface called "VAMI" where you can backup the configuration.

If I didn't answer as you expected, ask me again.

ARomeo

[DylanB17]

I did not specify, I am in 6.5.

Yes, but the vcenter is installed on one of the two machines (esx)

So if it is on the machine that breaks, it will not have time to give the order to resume the VM on the other machine?

[Alex_Romeo]

So if it is on the machine that breaks, it will not have time to give the order to resume the VM on the other machine?

Eh! yes, unfortunately it can happen. But the VCSA Virtual Machine is in the datastore, so other activities can be done to restore it on the good Host.

[DylanB17]

I'm having trouble understanding, can you summarize how high availability works?

Let's put the context, the vcenter server appliance is installed on esxi1, if esxi2 is shuting down what's going on?

And if esxi1 is shuting down what's going on?

[sjesse]

The simplest explanation I can think of is that vcenter keeps track of what hosts are available, and it knows what virtual machines are running on that host. If a host unexpectedly goes down, then vcenter automatically restarts those vms on another host. There are a lot of what ifs you can do but this is ha in the simplest. Its important to remember that you can't just shut off host(other than a hard shutoff), if vcenter is aware of your shutdown command ha doesn't kickin. I bring this up because I see a lot of people try testing ha by shutting a host off, that won't work you need to do things like remove a network cable.

[Alex_Romeo]

Hi,

If the vcenter is on Esxi_1:

If Esxi_2 dies, "HA" notices in advance that something starts to fail and turns off the VM and turns them on on the other host.

If Esxi_1 dies, "Ha" behaves the same way, realizes in advance that something is not working and shuts down the virtual machines and turns them back on the other host.

Then there is also the case in which for example the electricity goes off, the UPS unit ends and everything turns off. When you turn it back on, Esxi_1 does not restart. In this case "HA" did not turn off anything because everything worked well until the sudden end of the lack of electricity.

In this case, you need to perform other tasks to restore vCenter and vm.

ARomeo

[_BoRiS_]

Hi all,

Please don’t confuse vCenter HA and vSphere HA.

vSphere HA work with 2 esx hosts.

The need of 3 hosts is only for vCenter HA.

[sjesse]

doing the advanced install you can still do vcenter ha with 2, it complains but it works.