fartman
Contributor
Contributor

Difference between vmware HA & vmotion

Hi can anyone explain the difference between the 2?

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12 Replies
beth22
Enthusiast
Enthusiast

vMotion allows you to live migration a VM on one host to another without downtime.

HA provides high availability to VMs based on vMotion, HA restart VM in case of failure happened.

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fartman
Contributor
Contributor

Hi Thanks for the info;

i am confused as vmotion allows live migration but i've encountered vmware HA whereby the vm is powered-off and then powered-up again on another host.

Any idea when vmware decides to power-off the vm to perform a migration to another host

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beth22
Enthusiast
Enthusiast

OK, you can take an example, there are two hosts A and B in a cluster with HA enabled; If host A crashes, all VMs on that will be down too. In this case, VMware HA will help you restart those VMs to Host B, so there is no service downtime.

Please take a look at this video to a better understanding HA and Live Migration:

http://bit.ly/Kv8quV

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fartman
Contributor
Contributor

Hi thks for the info so if i were to perfrom a migration the vm can perfrom live migration without shutting down while vmware HA will require the vm on the crashed host to be powered up on the surviving host rite Smiley Happy

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schepp
Leadership
Leadership

If you do a migration, it can migrate without downtime with vMotion from Host A to Host B.

If your Host A crashes, your VM on that host crashed too. So it is in off-state. The only option HA has now is to start the crashed VM on Host B. vMotion cannot happen here since Host A and the VM are offline.

Regards

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Sreec
VMware Employee
VMware Employee

Hi All,

        One of my colleague had this query and he was bit confused after reading the above thread,so i'm updating the same.To be simple

1)HA will restart a VM, "HA will never Vmotion a VM "!!!!!

2.DRS will vmotion a VM .

Regard's

Sree

EMCIE|EMCISA-V2|EMCISA|VCP4|VCP5|MCP|MCTS AD2008

Cheers,
Sree | VCIX-5X| VCAP-4X| VExpert 6x|Cisco Certified Specialist
Please KUDO helpful posts and mark the thread as solved if answered
Kahonu84
Hot Shot
Hot Shot

I second what Sreec says. It is flat out wrong to say that HA and VMotion are related or connected in any manner. They are two completely different technologies. VMotion migrates a running VM from one host to another. HA restarts a VM on another host if the original host disappears for whatever reason. HA does not use VMotion.

masudhussain
Enthusiast
Enthusiast

Hi,

this thread is bit confusing. But it is absolutely correct that vmotion and HA both are deferent Technology. HA responsibility is to restart the VM only.

Now my question is , lets say in cluster two hosts are available HOST-A and HOST-B, in case host-A down all VMs running on this host will effected means the VMS will start on HOST-B. to start VMs which were running on HOST-A should register in inventory of HOST-B first thn VMS can be powered on. So, is it also responsibility of HA to register VM first on HOST-B thn start ?

Thanks & Regards,

Hussain

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Sundararajan
Enthusiast
Enthusiast

vMotion is live migration of a VM from one host to another without service interruption. ( No downtime in vMotion only single ping response will be lose)

HA will restart a VM from one host to other hosts available in the HA cluster, Ex: suppose a host not working or issues related to hardware, Network Etc... ( Downtime until VM is restarted to available host)

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KingofVM
Contributor
Contributor

Dear Friend,

Some direct answer of your direct question.

1. You can use vmotion for plan activity, whether HA work on accident activity.

2. Vmotion work without cluster, but HA work in cluster only

3. Whether HA sub components DRS use vmotion technology for function.

4.HA work on active:Dead host, whether vmotion work on Active:Active environment.


Thanks & Regards

NK

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manojrachuri
Contributor
Contributor

Guys sorry I'm not gud at vm ware I'm a biggner in it but the question is if HA is dependent on vmotion when does vmotion take place at the time of host failure .is it through vmotion the VM gets migrated to other host and then in that host the VM gets restarted...??give perfect answer at which exact place vmotion happens in HA at host failure condition in HA

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beth22
Enthusiast
Enthusiast

vSphere HA provides high availability for VM, it works without depending on vMotion.

When a host failure occur, vSphere HA try to restart VMs on the failed host to another running hosts that can satisfy resource requirements.