What if one of my esx server goes down ?

[blvsupport]

Hi im a new user to esx server. I installed and configured to esx server that ive put in my data center. I have now 4 vm running on my first esx server and i can vmotion them succesfully. One thing im wondering is what will happen if my esx server whos running 4vm goes down beceause of hardware problem lets say ?

Can you tell me what should i plan so that the other esx server take control of these vm automaticly

Thanks for your help !

Jac

[oreeh · Accepted solution]

That's what HA was made for.

If you have HA licensed you can configure HA in Virtual Center and if one host goes down the VMs will be automatically restarted on the second host.

[BryanMcC]

Sounds like you need to implement HA.. Take a look here at the overview...

http://www.vmware.com/pdf/ha_datasheet.pdf

Of course this is an add on to ESX Server Licensing or purchased with the Enterprise VI3... If you have it or want more deatils take a look here.

http://www.vmware.com/pdf/vi3_301_201_resource_mgmt.pdf

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[Chamon]

You will have to enable HA (high availability) in the edit settings on your cluster. The default is to have the VMs restart if one of your esx servers goes down. There is a short interuption in availability of the VM but the VM will be restarted on your second ESX host.

[blvsupport]

WOW the answer here are very fast

Thanks to all. I will check for Vmware HA

Thanks !

[blvsupport]

Ok we have the license for that feature. SO i create a new cluster with HA and DRS activated

Ive put 2 esx server in it to test it but there is no vm on them for now

But the problem is that on my 2 esx hosts i have this error "HA agent on 192.168.10.210 in cluster Test has an error"

Any idea what i did wrong or did not do ?

Thanks to all for helping me !

[BryanMcC]

1. Make sure that your ESX hosts can resolve each others FQDN

2. Make sure your ESX hosts can communicate with each other (ping)

3. Try right clicking on the host and selecting Reconfigure for HA

number 1 is most usually the case and can be solved be adding all ESX hosts to the hosts file in your service console or making sure you are using vaslid DNS for name resolutionn (and it is working).

Shared storage is also needed but I assume you havve that working.

Make sure if you add the hostnames and IPs to the /etc/hosts file they are nnot the shortnames and are all in lower case.. This will need to be done on both hosts.

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[oreeh]

Do your ESX hosts have a default GW configured?

If yes is this gateway reachable? Does it respond to a ping?

[blvsupport]

Ok i add all my ip address of my esx server in the /etc/hosts i reconfigure ha and its working now

Thanks !

Now what is the best thing to test if its working ?

Do i shutdown one of my esx server ? Should my vm on that server continue to run on the other esx server ?

Thanks again for your help it is very helpful !

[oreeh]

Now what is the best thing to test if its working ?

Pull the power chord on one of the servers, the VM should be started on the second ESX host.

[BryanMcC]

Yep... Shut it down and watch the VMs go down then come up on the other host... This isnt immediate so be patient but you should see them come back online..

I think I lose somewhere around 10 to 15 ping packets in my enviroment when I test pinging a guest that is using HA.

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[tdubb123]

This is a very interesting question. what if I have over 20vms running on one esx host and only have one other esx host to failover to? Also that esx host is having maybe like 15vms running on it. How is the second esx host going to handle this load? Or how can i tell if there is enough resources on the second node to handle all this? Is this where we would setup a third maybe fouth esx host and have nothing running on it and use it as a standby?

[BryanMcC]

Absolutely you can use more than one host.. I use four currently leaving enough resources on the cluster to handle a single host failure. Your configurations options are your choice. Depending on the number of hosts you have in your cluster and resources available you can allow for up to four host failures.

You can aslo use DRS as well as HA to distribute the load after failover.. Also you can setup reservations and or use admission control to not turn on certain less critical VMs after failover...

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[oreeh]

When using HA you have to make sure that if a host fails the other hosts can handle the load.

If your hosts can't handle the load not all VMs will be restarted.

This is one of the reasons why it is a bad idea to have two big boxes instead of maybe four smaller boxes.

In the first case a host failure means that you loose 50% of your capacity while with the second case you only loose 25%.

[blvsupport]

One thing i was wondering ?

1- If one of my esx server goes down, HA will transfer my vm to my other esx server. I tried that today and it work. The thing is in Virtual Center, the vm was still under the esx server that i turn off. Is it normal or i should view it under the other esx that was running ?

2- When i will power on the esx server that was down, will the vm goes back to it ?

Thanks its very intersting to learn all these infos

[blvsupport]

Another question guys :smileysilly:

Ressource Pool

1- Do we need this ?

2- If we need it how much we need ?

3- Is it one ressource pool by esx server ?

Thanks !

[oreeh]

The thing is in Virtual Center, the vm was still under the esx server that i turn off.

It takes some time until VC updates this

When i will power on the esx server that was down, will the vm goes back to it ?

Only if you have DRS enabled and DRS actually comes to play. This depends on the resource utilization of the hosts and how aggressive DRS is configured

[oreeh]

1- Do we need this ?

It depends...

I strongly recommend to read the Resource Management Guide

This will answer the other questions as well.

[BryanMcC]

In Virtual Center the VM will be shown under the cluster in parallel

with the ESX Servers.. Just looking at it you will not be able to tell

what ESX host it is running under. You will have to view the details of

the VM under Summary or Click on your second host and look under the

virtual machine tab.

[blvsupport]

Thanks OREEH for all info you gave me

One thing i was wondering too. I want to convert one of my print server wich is a domain controller too. Do you know if domain controller is ok to convert with vmware converter ? Did you try it ?

Any problems doing it ?

Thanks !