Re: VMotion as failover solution

  • From: Paul Drake <bdbafh@xxxxxxxxx>
  • To: exriscer@xxxxxxxxx
  • Date: Tue, 13 Dec 2011 08:21:37 -0500

I hate to say it, but this is an off-topic post.
Still, I'll bite.
Its like the BOFH's boss' idea of storing the data in the network.
Not on network storage, but moving about in all of that GigE kit with the

During vMotion events, the VM is in 2 places at once - doesn't that imply
that an outage is twice as likely to occur?

What is the goal?

With RAC, multiple instances would remove loss of an instance as a single
point of failure.
So if there is no fail, no failover event would need to take place.
If a session is lost due to loss of an instance, a reconnection will find a
surviving node.
If that's not good enough ... head down the path of transparent application
failover with pre-spawned sessions.

VMware vSphere is a client side application for administration.
If your vSphere connection drops, simply reconnect.
The ESX/ESXi hypervisors keep right on chugging along whether you're
monitoring them or not.

vMotion can be used manually to rebalance loads to move a virtual machine
to a different node in the cluster, to relocate VMs prior to taking a node
down for maintenance or used automatically by the distributed resource
scheduler in VMware to do battle with any other load balancers that are in
place in the environment to obtain nice sinusoidal graphs.

By itself, vMotion does not provide failover.
This may be a good point to start - or you might want to start at a more
general level.


On Tue, Dec 13, 2011 at 6:53 AM, LS Cheng <exriscer@xxxxxxxxx> wrote:

> Hi all
> I have a customer who is thinking in vmotion (VMWARE vSphere) as database
> failover solution instead of active/passive cluster or RAC.
> I havent used this tool before, anyone know how does it work?
> --
> --
> //


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