vmotion

[nimicyy]

hi,

Is it safe to use vmotion to move a VM (with linux that has nfs or cifs  shared mounted inside VM)?

Is it safe to move with vmotion a VM that is very high loaded?either the i/o traffic is very high or the cpus are very loaded.

if there inside VM is high i/o traffic can be a delay in moving the VM to other host?

[NicolasAlauzet]

Hi there,

Yes, it is safe. vMotion offers zero downtime.

Here you have an explanation of how vmotion works for you to have a better understandment:

VMware vMotion, how it works - Part 1 Introduction - Opvizor | Opvizor

https://www.vmware.com/products/vsphere/vmotion.html

[nimicyy]

is safe because memory content of vm is moved?

[NicolasAlauzet · Accepted solution]

Yes, there is the detailed list of things that happen in vMotion... Anyways, sometime testing it is the best way to gain confidence! But dont worry, it works just fine

1. The first step is to ensure that the source VM can be operated on the chosen destination server.
2. Then a second VM process is started on the target system and the resources are reserved.
3. Next a system memory checkpoint is created. This means all changes to the source VM are written to an extra memory area.
4. The contents of the system memory recorded at the checkpoint are transferred to the target VM.
5. The checkpoint/checkpoint-restore process is repeated until only the smallest changesets remain in the target VM’s memory.
6. The CPU of the source VM is stopped.
7. The last modifications to the main memory are transferred to the target VM in milliseconds.
8. The vMotion process is ended and a reverse ARP packet is sent to the physical switch (important: Notify Switches must be activated in the properties of the virtual switch). Hard disk access is taken over by the target ESX.
9. The source VM is shut down. This means the VM process on the source ESX is deleted.