Q:

Is there downtime involved when using Azure vertical scaling?

I have a two websites on a VM with WHM/cPanel and MySql.
I am looking to move this into Azure and use vertical scaling. Visits to the website are usually stable but three or four times a year there is a big increase in traffic which historically has caused big problems for the existing host.
I am looking to move it into the A5-A7 range of servers for the vertical scaling.
I cannot find anything anywhere about whether there is any downtime involved when Azure scales up my VM from A5 to A6 or whatever.
Does anyone have any experience with this and can give me a definitive answer as to whether there is downtime when using vertical scaling, and if there is any downtime involved then the kind of downtime I would expect
Thank you for your time.

A:

Yes, it will incur downtime. Post on it
Azure will restart your VM.
Quote from the page (I highlighted the important bit):

When considering the ability to resize virtual machines there are
  three key concepts that will impact how simple it is to change the
  size of your VM.

The region in which your VM is deployed. Different VM sizes require different physical hardware. In some instances, an Azure region may
  not contain the hardware required to support the desired VM size. All
  Azure regions support the VM sizes Standard_A0 – A7 and Basic_A0 – A4.
  You can then find which other VM sizes are supported in each region
  under the Services tab of the Azure Regions web page.
The physical hardware currently hosting your VM. If the physical hardware currently running your virtual machine also supports your
  desired new size, then it is very easy to change the VM size through a
  simple size change operation which results in a VM reboot.
The deployment model used for the VM. The two deployment models are Classic and Resource Manager. The Resource Manager model is the newer
  model, and it supports some ease of use functionality not available in
  the classic deployment model.

