VMware and Application HA


I have a virtual env with 2 VMs (or the same host)  in which I run several application on top of a RHEL OS.

What I was looking for is what are the options (maybe pros/cons) to achive app. HA between the VMs.

In order to have, in case a appl. fails on the VM#1, it would automatically failover to the VM#2 (even if the VM#2 is on the same host or not).

I checked the VCS (Veritas) for ESX and the App HA.... but I dont know much about them...

Can you guys maybe point out reliable articles and if in your opinion one is better than the other in terms of easy to implement, less cost, more reliabel..etc?

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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
You could also use Double Take or VMware FT, HA, restarts the VM on another host if the application fails, VMware FT, is two machine's in lock step with each other.....but you have to be careful with FT, because if the application failed on VM1, (VM2) which is in lock step, it would also fail.

So is this Application Protection? you require, so why not think of Clustering ?

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joaotellesAuthor Commented:
Just a side note (not sure if relevant) but I only have one vCenter that manages theses VMs.
joaotellesAuthor Commented:
Clustering would be a good idea.... like having Veritas on top of the VMware (n ot sure if that what you meant)... but I think in terms of cost would be more expensive in order to achieve basically the same thing....

The goal here is to have HA for the apps... by HA I mean if the application fails on the VM#1, the Syamntec HA (that I already have) would try to start the appl on the same VM 3 times (as per my configuration). And if its still failing, them something else (maybe  this vSphere App HA) to have the app starting in a VM#2.

If the host fails the vMotion would take care of it failing over the whole VM to the other host.

Thats my take on it... not sure if its correct or the most efficient one.....

Maybe I dont even need the Symantec HA that I already have....

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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Just a little thing about vMotion - this only migrates Live VMs, from one host to another!

VMware HA, is the function which restarts other VMs, if the host fails or Appication fails, BUT, there is approx 1-2 minutes of downtime, whilst the entire VM is restarted.

vSphere App HA, will restart a service x number of times.

You already have a Symantec HA.....?
joaotellesAuthor Commented:
Yes I do (evaluation period).

The thing with the Symantec HA is that it only restarts the Appl. on the same VM.

So, I was looking for something that would failover the Appl. from VM#1 on VM#2.

Lets say the appl. has a problem in the VM#1 and crashes (but the VM is still On)... with the Symantec HA, the Appl will try to restart X times on the same VM, and if for whatever reason it cant make it, it will be in the 'failed' state and nothing else will be done...

With vMotion (my understanding). If a VM fails on the Host#1, then the whole VM will be migrated to the Host#2. Its a dif. "layer" of HA compared to the Appl. HA Im talking about... (maybe this is the VMware HA you were talking about and I misunderstood it for the vMotion)

Talking about the VMware vSphere App HA, my understanding is that with it, if the Appl (not the VM), fails on the VM#1, it would failover to the VM#2. Only the Appl., not the whole VM.

It would have the same "effect" as the Veritas Cluster Service, that when a Appl. fails on the Node1, it fails over to the Node2.

If that is not the case... then what Im looking for is the VCS implemented for virtual envs (VMware) and if there is any VMware product that would do the similar job as the VCS does for the applications. (which is fail it over to another VM (node) in case of a crash).

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Sorry, vMotion does not do this. vMotion, is a feature you can use to manully migrate a VM from one host to another.

VMware HA is a function, which will restart a VM, on another host, if the host has a failure.

All VMs will be restart on another host.

Now, there is another function of VMware HA - VM and Application Monitoring - it can be used to monitor the heartbeats of an application, and if the application fails, then restart the VM on another host.

This is a licensed function with VMware vSphere, but also requires a SAN or NAS (shared storage) and at least two hosts.
joaotellesAuthor Commented:
Also, I could not find any "updated" document that would point out if the RHEL7 is compatible with any VCS version running in a VM.,,, DO you know if this would be a problem...
joaotellesAuthor Commented:
Tks for the reply.

Have you ever worked with these? VMware HA - VM and Application Monitoring ...

Any input by comparing VCS w/ vmware and this VMware HA - VM and Application Monitoring ?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
I've not worked with the Veritas product for many years.

I've only worked with VMware HA, Double Take products.

Application Monitoring does require development time, it's not an off the peg solutions, because you need to establish a heartbeat with the application, to monitor, if the App is down.

This is using VMware HA with Application, monitoring, or using VMware App-V Monitoring, and using vFabric

see here


Also it comes down to your budget, which you've not mentioned.....

e.g. do you have shared storage or just local storage ? products from Double Take may be better...
joaotellesAuthor Commented:

I have a shared storage... Not sure about the budget yet..

Checking the options and per what I understood here is my summary:

1- vSphere App HA - which is essentially the same thing as the Symantec HA. But also - if you are running one of the supported applications - then App HA will recognize that a service has failed, it will try and restart that service (X amount of times - according to your settings) and if that does not work, it will restart the machine.

2- VMware HA - VM and Application Monitoring :

For the HA VM monitoring, it will restart a VM if:
a- That VMs VMware Tools heartbeats are not received in a set period of time (see below for details)
b- The VM isn’t generating any storage or network IO (for 120 seconds by default, though this can be changed using the following advanced cluster level setting: das.iostatsInterval)

For the Application Monitoring, it was confusing for me to see if the App HA and this Application monitoring are actually the same thing or not...

I found this statement in one of the docs:
"To enable Application Monitoring, you must first obtain the appropriate SDK (or be using an application that supports VMware Application Monitoring) and use it to set up customized heartbeats for the applications you want to monitor. After you have done this, Application Monitoring works much the same way that VM Monitoring does. If the heartbeats for an application are not received for a specified time, its virtual machine is restarted."

So I think its essentially the same thing...

3- the VCS for VMware, which would give me basically all the functionalities I have for Appl failover..etc... but maybe the most expensive solution...


Is this a right undertanding of the #1 and #2 (The VMware products?)

I will also check the Double take products.

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Almost, VMware HA it's included, you need to do some work, if you want to monitor your Application Heartbeats. Very little if you just want to watch VM heartbeats using VMware Tools.

Your option one (1), also needs the use of vFabric. (another licensed product!).

Many different methods to achieve this.
joaotellesAuthor Commented:
Tks! I will try all these methods and decide from there afterwards...

I have to check which method my applications complies best as well...
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