Nested hypervisors?
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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?
But yes, working around the requirements of super shitty vendors is another reason. Adding complexity and fragility to circumvent terrible rules.
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@obsolesce 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?
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.
Many do, it's surprisingly common in shitty software, which most software is.
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@wirestyle22 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.
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)
No, Devs don't need access to anything like that. Nor would they need a SAN. Devs write code, like any other end user.
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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?
Right, that's a common thing. Making workloads like that is standard. That's what cloud does, for example.
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@obsolesce said in Nested hypervisors?:
@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.
What legit dev purpose would use full VM control rather than just provisioning.
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@wirestyle22 said in Nested hypervisors?:
@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.
Think of any cloud service. Amazon, Vultr, Digital Ocean... they all do this.
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@dustinb3403 said in Nested hypervisors?:
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.
Likely don't even know that there are tools, just repeating words that they've heard.
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@obsolesce 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?
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.
This would work, as only one vendor supports the virtualization of another hypervisor (and only for a niche use case) that I'm aware of.
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@scottalanmiller said in Nested hypervisors?:
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?
This is commonly done with a Cloud Management Product that overlays the hypervisor (OpenStack, vRealize Autiomation, etc, PKS etc) that can manage the multi-tenancy etc.
Now some hypervisors support some provisioning options others don't (Instant Clones are a unique one, that allow cloning a running VM with thin memory) that may make some things more efficient -
@obsolesce said in Nested hypervisors?:
Nested (virtual) ESXi is not officially supported by VMWare, so that's not a production scenario anyways.
Technically it's used for the vSAN Witness (which is just a ESXi VM). It's used internally for QE testing, It's used for the hands on labs also.
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@dustinb3403 said in Nested hypervisors?:
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.This wouldn't be supported by any VMware appliance vendor I"m aware of, and VMware certainly wouldn't support it.
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@storageninja This was just a random example of a fictitious scenario.
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@storageninja said in Nested hypervisors?:
@obsolesce 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?
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.
This would work, as only one vendor supports the virtualization of another hypervisor (and only for a niche use case) that I'm aware of.
Most vendors specify that X hypervisor must be there, and specify nothing of what is beneath it.
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@storageninja said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
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.This wouldn't be supported by any VMware appliance vendor I"m aware of, and VMware certainly wouldn't support it.
But would be supported by the application vendor.
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@scottalanmiller said in Nested hypervisors?:
@storageninja said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
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.This wouldn't be supported by any VMware appliance vendor I"m aware of, and VMware certainly wouldn't support it.
But would be supported by the application vendor.
I've never seen a application vendor that mandates a hypervisor, but doesn't care if it's deployed in a non-supported configuration. I could see EPIC and the like having a good laugh though if you ask them.
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@storageninja said in Nested hypervisors?:
@scottalanmiller said in Nested hypervisors?:
@storageninja said in Nested hypervisors?:
@dustinb3403 said in Nested hypervisors?:
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.This wouldn't be supported by any VMware appliance vendor I"m aware of, and VMware certainly wouldn't support it.
But would be supported by the application vendor.
I've never seen a application vendor that mandates a hypervisor, but doesn't care if it's deployed in a non-supported configuration. I could see EPIC and the like having a good laugh though if you ask them.
You mean you've never seen a good vendor do that right? I've definitely seen it.
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@wirestyle22 said in Nested hypervisors?:
I've never seen a application vendor that mandates a hypervisor, but doesn't care if it's deployed in a non-supported configuration. I could see EPIC and the like having a good laugh though if you ask them.
You mean you've never seen a good vendor do that right? I've definitely seen it.
Who is a better EMR vendor than EPIC? They are kinda the gold standard and the #2 (Cerner) isn't going to support it either.
Even if we get into the smaller players (Care4, AllScripts) that are not supported either. That's also ignoring that the DB vendors in these cases (Cache, Oracle, etc) are going to not support it.Try telling a chief medical officer, or head a practice "Hey... so we are going to go with this no-name vendor for the application you spend 90% of your time in, because they would support Hyper-V on KVM on ESXi!"
What vendor and what nesting have you seen supported?
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@storageninja said in Nested hypervisors?:
@wirestyle22 said in Nested hypervisors?:
I've never seen a application vendor that mandates a hypervisor, but doesn't care if it's deployed in a non-supported configuration. I could see EPIC and the like having a good laugh though if you ask them.
You mean you've never seen a good vendor do that right? I've definitely seen it.
Who is a better EMR vendor than EPIC? They are kinda the gold standard and the #2 (Cerner) isn't going to support it either.
Even if we get into the smaller players (Care4, AllScripts) that are not supported either. That's also ignoring that the DB vendors in these cases (Cache, Oracle, etc) are going to not support it.Try telling a chief medical officer, or head a practice "Hey... so we are going to go with this no-name vendor for the application you spend 90% of your time in, because they would support Hyper-V on KVM on ESXi!"
What vendor and what nesting have you seen supported?
Epic and Cerner are insanely expensive EMR's, EPIC even more so than Cerner. I used Cerner at Barnabas Health. It doesn't apply to most people here.
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@scottalanmiller said in Nested hypervisors?:
This would work, as only one vendor supports the virtualization of another hypervisor (and only for a niche use case) that I'm aware of.
Most vendors specify that X hypervisor must be there, and specify nothing of what is beneath it.
Beyond the performance hit on the IO path (lot of interrupts make this not efficient) this is the same as running on non-supported hardware.
If a vendor uses Oracle DB and says "We use Oracle" and you run Oracle on a x86 emulator on a Raspberry Pi, I can see you trying to claim a loophole, and I can also see the vendor not wanting to support you.
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@wirestyle22 said in Nested hypervisors?:
Epic and Cerner are insanely expensive EMR's, EPIC even more so than Cerner. I used Cerner at Barnabas Health. It doesn't apply to most people here.
All-Scripts support (Small Clinical EMR) is not going to support this config either.
