I have just downloaded "ubuntu-14.04.1-desktop-amd64.iso" and "ubuntu-14.04.1-server-amd64.iso" through "http://www.ubuntu.com/".

Please can someone confirm the maximum RAM that is supported.

According to many sites, Maximum RAM supported by the OS

ubuntu-14.04.1-desktop : " 2^64 bytes " -- Kindly confirm

ubuntu-14.04.1-server : " 2^64 bytes " -- Kindly confirm

  • 1
    What motherboard do you have that can use that much RAM?
    – oldfred
    Dec 7 '14 at 17:48
  • I think for all practical considerations it is limited only by your hardware.... I've seen IBM x3850 X6 boxes running with 2TB of ram and I'm pretty sure there is no artificial limit in the Linux kernel.... Sep 3 '15 at 14:11

Maximum RAM supported by Ubuntu:

  • Ubuntu 32-bit + PAE (Physical Address Extension) - 64GB RAM although the memory access above 4GB will be slightly slower. PAE is now the standard for 32-bit Ubuntu, so there is no need for enabling it.

  • Ubuntu 64-bit - A 64-bit computer will be able to address up to 16.8 million TB (16 exabytes) although constraints are in place that limit this to around 1TB.

Reference: Ubuntu Documentation: 32-bit and 64-bit Community Help Wiki

  • @fossfreedom the information on max core count was nice. Pity it had to go.
    – muru
    Dec 7 '14 at 17:37
  • 1
    @muru The x86_64 Linux kernel can handle a maximum of 4096 processor threads in a single system image. This means that with hyperthreading enabled, the maximum number of processor cores is 2048. There are computers with more than 2048 processor cores, but these run as clusters where several Linux kernels cooperate, connected with a high speed interconnect. From the most current kernel 3.13 in Ubuntu 14.04 in /usr/src/linux-headers-3.13.0-40/arch/x86/Kconfig : config NR_CPUS ---help--- If CPUMASK_OFFSTACK is enabled, the maximum supported value is 4096, otherwise the maximum value is 512.
    – karel
    Dec 7 '14 at 17:42

First, the only difference between server and desktop is what packages are installed by default; both run the same kernel. The maximum amount of memory supported on both is the maximum amount your hardware supports. The max for amd64 cpus is 2^48 bytes ( the architecture defines that the higher order bits are reserved ), but motherboards invariably have a lower limit they impose.

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