Essentially I'm after something like this, but for Ubuntu Server 14.04 LTS.

I'm trying to create some KVM guests with very large 1TB+ RAM (through OpenStack Nova). I can boot the 1TB VM fine, but I get a kernel panic with the 2TB flavor. Just wondering if I'm running into a kernel limit with the Ubuntu KVM implementation?

  • What kind of kernel panic do you get? In the host or in the guest? And I assume you are talking about the virtual hard drive sizes, right? I am not aware of hardware that support 2TB RAM. What kind of storage backend are you using with KVM? qcow2 files, LVM, physical disks, etc. And please include the exact kernel version you are using uname -a and an excerpt of the kernel traceback you probably see on your screen. Please edit your question to include all these details so we can help you better.
    – gertvdijk
    May 8, 2015 at 7:25
  • If you indeed mean RAM maximum sizes, then 1TB is the upper limit for older Linux kernels (source). So please share also what kind of guest OS you are using and kernel (also uname -a from within the guest OS).
    – gertvdijk
    May 8, 2015 at 7:27

1 Answer 1


This has been answered here https://serverfault.com/questions/343756/kvm-maximum-number-of-cores-and-amount-of-memory-for-vms

Basically VM core is a process running is a host, so there is no limits. But if you think can you run a process with 2TB in a host with 1TB physical memory, its is possible if you have at least 1TB swap. But it must be very, very slow. So there is no mean to run in a host VM that has more memory than host has. And there is no mean to define more cores to VM than host has.

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