Paravirtualization in ESXI

[Tommyfayyad]

Hello All

I would like to know if ESXI v5 supports CPU paravirtualization or just SCSI paravirtualization?

Thanks

[Abhilash Basavarajaiah]

AFAIK its just SCSI paravirtualization. CPU Paravirtualization needs modification of OS kernel to make it understand its running on a virtualizaed environment and work accordingly unlike full virtualization where the OS will think its installed on a physical server.

[john23]

VMware only support full  CPU virtualization. Currently with Hardware assist virtualization (intel-VT and AMD -v), there is no need of Binary translation and Para virtualization.

Other than SCSI, VMware tools provides backdoor for time synchronization as well vmxnet also is para virtualized device driver.

-A

[Tommyfayyad]

Thank you John

This is what I expected. but there are some posts on the net saying that paravirtualization is possible if the Guest OS supports VMI. see:

http://techiesweb.com/wp-content/uploads/2010/10/clip_image0028.jpg

Paravirtualization with ESX | Virtual Lifestyle

can you advice?

[john23]

In 2005, VMware proposed a transparent paravirtualization interface, the Virtual Machine Interface (VMI), as a standardized communication mechanism between the guest operating system and the hypervisor.

Check this paper:http://www.vmware.com/files/pdf/VMware_paravirtualization.pdf

Section: VMware’s Transparent Paravirtualization Balances Performance Benefits with Maintenance Costs

[Abhilash Basavarajaiah]

As i already mentioned it requires kernel modification. All the Windows servers cannot be paravirtualized as they come with non-modifyable kernel. here in your example link they are talking about modifying the ubuntu kernel to make it give better performance. I think it works only with ubuntu and no other OS. or maybe couple of linux kernels. Which OS are you trying this for?

[Tommyfayyad]

I am in fact using Linux 3.6.11, which I built it myself.

I built 2 versions: one with PARAVIRT enabled and one disabled. I am doing some tests on them and I see that both versions gave same results, while I expected the paravirtualization to be better.

[Abhilash Basavarajaiah]

Update: Support for guest OS paravirtualization using VMware VMI to be retired from new products in 2010-2011 | Guest OS…

May be its not working anymore. I Seriously do not understand why the option is still present when they don't support it.

[Tommyfayyad]

Thanks John

I have read this paper few times, and I am using ESXI 5.1 and it was impossible to create a paravirtualized VM. so I was wondering why VMware proposed paravirtualization but they are not using it.

so do you mean that in ESXI, paravirtualization is not implemented anymore?

Regards

[Abhilash Basavarajaiah]

After 4.1 VMware does not support VMI anymore

VMware KB: Migrating VMI-enabled virtual machines to platforms that do not support VMI

[john23]

May be due to Hardware support(VT) came up, one of the reason VMware is not supporting para virtualization.

[Abhilash Basavarajaiah]

I think it was discontinued because it was supported by only couple of linux distros and it used to cause lot of instability to others VM's which did not support it when it was turned on. And also may be because of VT.

[Tommyfayyad]

Thanks a lot Abhilash and Johan.

this really helped and removed my doubts.

Best Regards

[Abhilash Basavarajaiah]

Just checked in 5.5 host. i don't see it anymore. So better not use it. glad we could help :smileyhappy:

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