Nested ESXi 5.1 on IBM x3850 M2 (7141-xxx model)

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For my test lab I use an IBM x3850 M2 model 7141-3RM. Its a 4 socket server, with 4 cores per socket and 96Gb Ram running nested ESXi hosts.

Until recently, I was still running ESXi 5.0 on the physical host, with nested ESXi 5.1 hosts which worked perfectly.

Recently I decided to upgrade the physical host to ESXi 5.1.

Problem: My nested ESXi 5.1 hosts can no longer run 64bit VMs.

Now why is that? The Intel E7330 supports Intel-VT-x w Extended Page Tables (see Intel’s website here) or so they say?!

IntelEssentials IntelAdvancedTech

As mentioned by William Lam (@lamw) on his blog (VirtuallyGhetto)

A quick way to verify whether your CPU truly supports both Intel-VT+EPT or AMD-V+RVI, you can paste the following into a browser:

https://[your-esxi-host-ip-address]/mob/?moid=ha-host&doPath=capability

So, after running this on my host, I got the following result

nestedHVsupport

So that’s a bummer, I cant run ESXi 5.1 on my physical host with nested ESXi hosts running 64 bit VMs.

Note: 32bit VMs run fine.

So, Intel are telling fibs about what this processor can do, but that doesn’t help solve the issue.

Solution: If you have this processor in your test lab and/or have the IBM x3850 M2 model 7141-xxx (or you obtain one as they are a great low cost option for a test lab) run ESXi 5.0 on the physical host, and run ESXi 5.1 nested and you can run 64bit VMs.

4 thoughts on “Nested ESXi 5.1 on IBM x3850 M2 (7141-xxx model)”

  1. Hi Josh,

    I found this interesting and a bit confusing. Surely if you can run nested 64bit VM’s on ESXi 5.0 and not ESXi 5.1 (on the same hardware platform), then it points to the software, not the CPU.

    The CPU is clearly capable and has this feature set included because you run it that way under ESXi 5.0? I wonder if there is some other reason that might explain this?

    You gave a link on how to check host compatibility. Do you get a different result when checking this on 5.0 and 5.1?

    Might have to review what I am planning for my training lab.

    Reply ↓

    • Hi David,

      Thanks for your comment.

      The issue is that ESXi 5.0 did not support EPT, as such nested 64bit VMs worked under ESXi 5.0 as EPT was not a requirement (since it wasn’t detected/supported).

      Now that ESXi 5.1 supports EPT, VMware has made this a requirement (of the CPU) to support 64bit guests under the nested host. (As Performance is severely impacted without it)

      So unfortunately, the CPU type (E7330) doesn’t in fact support EPT, and now that VMware supports (and detects) EPT, running 64bit VM guests under nested hosts fails as the CPU doesnt support it.

      Hope that clears up any confusion.

      Reply ↓

  2. Hi Josh,
    I have 80GB of RAM, do you know if VMware now offers a way to get over the RAM 32GB limit for 5.0 vSphere, now the limit have gone after v5.5.

    Regards,
    Adam

    Reply ↓

    • I believe the 32Gb limit is just the free edition, if you use an evaluation or licensed edition you should be able to have maximum supported RAM >1TB per host. Eval editions can be up to 365 days so that’s not bad for a lab.

      Reply ↓

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