VMware  question  Vmotion vs Cluster vs DRS

mokkan
mokkan used Ask the Experts™
on
From my understanding I have interpreted as below, is this correct?


Vmware Cluster(HA) - If we have cluster configured and if one of the ESX hosts failed, all the VMs which are running here will move over to another ESX host in the cluster farm without any downtime or reboot.

Vmware Vmotion: Vmotion uses to move VMs between the datacenter without down time

Vmware DRS:  If we have enabled DRS, when usage is high on memory or cpu, it will move over to another ESX host in farm.

If'm wrong please correct me.
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Top Expert 2010
Commented:
1. There is slight downtime with HA; a VM "restarts" on another host, albeit the 'restart' is miniscule in time.
2. VMotion is a live VM migration withIN a datacenter, not across separate VMware datacenter objects (this is coming though)
3. VMs will be VMotioned to other hosts if resources of current host a VM(s) is on get 'strained'.

Hope that helps.

~coolsport00
Vmware Cluster(HA) - If we have cluster configured and if one of the ESX hosts failed, all the VMs which are running here will move over to another ESX host in the cluster farm without any downtime or reboot.

No - your VM's will all reboot.  You are thinking of fault tollerant settings.

Vmware Vmotion: Vmotion uses to move VMs between the datacenter without down time

Yes - but you must have shared storage and a dedicated VMware network to do this

Vmware DRS:  If we have enabled DRS, when usage is high on memory or cpu, it will move over to another ESX host in farm

In theory, that's what is supposed to happen.
Top Expert 2010
Commented:
I highly recommend getting the VMware vSphere 4.1 HA and DRS Technical Deepdive book by Duncan Epping/Frank Denneman for more info.

~coolsport00
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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
1. VMware Cluster (HA) - No.

If a VMware ESX Host in a  cluster fails with HA enabled. The virtual machines that were running on that host, will be restarted on other hosts in the cluster.

2. Correct

3. Correct.
Top Expert 2010
Commented:
It is incorrect that HA will cause zero down time. With HA a vm running on a failed host must be powered up on another host in the cluster and go through its boot process.

For zero downtime for a vm on a failed ESX(i) host look into Fault Tolerance.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
Top Expert 2010
Commented:
The Availability Guide also explains more:
http://www.vmware.com/pdf/vsphere4/r41/vsp_41_availability.pdf

Author

Commented:
For the DRS event, there is no restart event right? Only for HA there is a restart? Am I right?
Top Expert 2010
Commented:
Correct...
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
VMware vSphere 4.1 HA and DRS Technical deepdive (Volume 1)

By Duncan Epping and Frank Denneman

ISBN-10: 1456301446
ISBN-13: 978-1456301446

Written by Duncan Epping and Frank Denneman, both of whom are Consulting Architects at VMware and are perceived by the

industry as Subject Matter experts on VMware High Availability and VMware Distributed Resource Scheduler.
This book zooms in on two key components of every VMware based infrastructure. It covers the basic steps needed to create

a VMware HA and DRS cluster, and goes on to explain the concepts and mechanisms behind HA and DRS which will enable you to

make well educated decisions. You will get the tools to understand and implement e.g. HA admission control policies, DRS

resource pools and resource allocation settings and more.

On Amazon US

[Paperback]

http://www.amazon.com/gp/product/1456301446?ie=UTF8&tag=yellowbricks-

20&linkCode=as2&camp=1789&creative=9325&creativeASIN=1456301446

[ebook]

http://www.amazon.com/dp/B004V49JGW/ref=as_li_tf_til?tag=yellowbricks-

20&camp=0&creative=0&linkCode=as1&creativeASIN=B004V49JGW&adid=0ED4RKK85G6ZTGTH9ENP

on Amazon UK


[Paperback]

http://www.amazon.co.uk/Vmware-Vsphere-4-1-Technical-Deepdive/dp/1456301446/ref=sr_1_2?

ie=UTF8&s=books&qid=1305637596&sr=8-2


[ebook]

http://www.amazon.co.uk/VMware-vSphere-4-1-technical-deepdive/dp/B004V49JGW/ref=sr_1_1?ie=UTF8&s=digital-

text&qid=1305637596&sr=8-1

Available in Europe from

http://www.comcol.nl/detail/73133.htm

Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
Kerem ERSOYPresident
Commented:
>Vmware Cluster(HA) - If we have cluster configured and if one of the ESX hosts failed, all the VMs
> which are running here will move over to another ESX host in the cluster farm without any downtime
> or reboot.

In fact when a system ina cluster just shuts down then you can't move the host with all the state data. You just reboot the failing VM in another host.

> Vmware Vmotion: Vmotion uses to move VMs between the datacenter without down time

This is correct

> Vmware DRS:  If we have enabled DRS, when usage is high on memory or cpu, it will move over > to another ESX host in farm.

I t will move without rebooting correct. But farm not always. I mean if you2ve licensed VMWare for 4 servers then your form consists of these 4 servers. The cloud technology is similar but this is not a cloud technology.

Besides both technologies require you to keep your VM images on a Storage which all VMWare hosts could access.

Cheers,
K.



Author

Commented:
Thanks a lot all of you.

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