Nested hypervisors?
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@scottalanmiller said in Nested hypervisors?:
KVM provides "working but experimental" nesting.
Which is fine... because I can't imagine having to use it outside of testing or lab scenarios.
I didn't know KVM still had it in experimental mode:
https://www.linux-kvm.org/page/Nested_Guests
For completeness:
https://docs.fedoraproject.org/en-US/quick-docs/using-nested-virtualization-in-kvm/ -
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Virutalbox is kinda useless as basic things like USB 3 drivers require a 5000$ license.
ESXi has supported nesting longer than all of them, and has a few production use cases for hypervisors on hypervisors.
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@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
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@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
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@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
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@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
Vendors never require a specific hypervisor. If they did, you certainly wouldn't nest it. And if it was a consideration, you'd find a different vendor.
Really, it's for lab/testing.
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@obsolesce said in Nested hypervisors?:
Vendors never require a specific hypervisor.
That's actually not true. I have seen at least one that required ESXi, but you could make the caveat that there are no GOOD vendors.
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@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
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@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
I haven't ever had the need to even look at attempting this so I don't know. But lets say you're a Hyper-V shop and have a business requirement you have to run an appliance of some kind that is tailored to ESXi, this would be a case where you'd likely nest.
Rather than building another hypervisor fleet.
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@obsolesce said in Nested hypervisors?:
Really, it's for lab/testing.
Alright, I meant real-world but I didn't say that. That's on me.
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@obsolesce said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
Is it common for a Dev to need access to the hypervisor themselves? Sounds weird but I don't work with devs a lot (yet)
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@obsolesce said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
Even in this case, would nesting be required?
Why not do permission based limitations so you can provide a Dev with access to create/destroy as many VM's as he/she needs within the constraints of your pool or resource limits?
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@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
I haven't ever had the need to even look at attempting this so I don't know. But lets say you're a Hyper-V shop and have a business requirement you have to run an appliance of some kind that is tailored to ESXi, this would be a case where you'd likely nest.
Rather than building another hypervisor fleet.
Nested (virtual) ESXi is not officially supported by VMWare, so that's not a production scenario anyways.
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@dustinb3403 said in Nested hypervisors?:
@obsolesce said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
Even in this case, would nesting be required?
Why not do permission based limitations so you can provide a Dev with access to create/destroy as many VM's as he/she needs within the constraints of your pool or resource limits?
I mean, isn't it likely to be his own host completely? I wouldn't let someone manage a host I'm responsible for. At that point he just manages it right? No need for nesting.
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@dustinb3403 said in Nested hypervisors?:
would nesting be required?
Only if full hypervisor control is required. I almost did this for a dev... well I did, but it turned out in the end that he wanted Virtualbox... so that's what he got.
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@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@obsolesce said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
Even in this case, would nesting be required?
Why not do permission based limitations so you can provide a Dev with access to create/destroy as many VM's as he/she needs within the constraints of your pool or resource limits?
I mean, isn't it likely to be his own host completely? I wouldn't let someone manage a host I'm responsible for
Well. . . no
Just as an example, with XenServer (and XO) you can create users and give them access to a specific pool or set amount of resources on any server in the pool, and to what guests they could affect.
So this would allow the user to do their job without the need for additional hardware or nesting. Unless their job was to develop on a specific hypervisor.
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@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@obsolesce said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
Even in this case, would nesting be required?
Why not do permission based limitations so you can provide a Dev with access to create/destroy as many VM's as he/she needs within the constraints of your pool or resource limits?
I mean, isn't it likely to be his own host completely? I wouldn't let someone manage a host I'm responsible for
Well. . . no
Just as an example, with XenServer (and XO) you can create users and give them access to a specific pool or set amount of resources on any server in the pool, and to what guests they could affect.
So this would allow the user to do their job without the need for additional hardware or nesting. Unless their job was to develop on a specific hypervisor.
Gotcha. Haven't ever needed to use that functionality. I was worrying about stuff like thin-provisioning but if you can limit the resources that's great.
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Which I would be wary of anyone who says "I must do my development work on <insert hypervisor>". Because I know they are almost certainly doing the work within a guest and are just comfortable with the tools.
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@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@obsolesce said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
@emad-r said in Nested hypervisors?:
Yup go figure for value, Virtualbox has no intention of doing this amazing feature since 2011
Maybe I'm missing something but why in the world would I ever want to use nested hypervisors? Vendor requirements?
If a vendor is stating that they only support a specific guest OS on a specific Hypervisor they had better be supporting the entire stack and not just an application that is on the guest. . .
What scenario is a nested hypervisor useful in any way?
The only realistic "production" usage for nesting, would be if you for example want to give a Dev his/her own hypervisor to cycle through VMs... or some similar situation where you can't dedicate hardware to.
Even in this case, would nesting be required?
Why not do permission based limitations so you can provide a Dev with access to create/destroy as many VM's as he/she needs within the constraints of your pool or resource limits?
I mean, isn't it likely to be his own host completely? I wouldn't let someone manage a host I'm responsible for
Well. . . no
Just as an example, with XenServer (and XO) you can create users and give them access to a specific pool or set amount of resources on any server in the pool, and to what guests they could affect.
So this would allow the user to do their job without the need for additional hardware or nesting. Unless their job was to develop on a specific hypervisor.
To get that kind of control wiht Hyper-V , you need SCVMM.
We don't have that anymore.
On top of that, he was good with KVM. So I had created a nested KVM host on Hyper-V which was great for him for a while. But he was coming from VirtualBox, and didn't have time to convert all the stuff and whatever else that was involved.
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@obsolesce yeah I'm not saying there isn't a reason or whatnot for using nested hypervisors. Just discussing the possible use cases I could imagine for it and where it may or may not make sense.
