Maximum Memory and CPU Limitations for Linux Server

You should always aware of maximum amount of memory and maximum number of CPU supported by Linux systems / server.


This is an essential task for making out decisions. You must consider at least AMD and Intel platforms, tested under RHEL 5 only:

Intel x86

  • Maximum CPUs: 32 (including logical CPUs)
  • Maximum memory: 64GB
  • Maximum filesize: 8TB
  • Maximum filesystem size (ext3): 16TB
  • Maximum per-process virtual address space: 4GB

AMD 64/EM64T (CentOS 5.x/RHEL 5.x Linux specific info)

  • Maximum CPUs: 256
  • Maximum memory: 256GB
  • Maximum filesize: 8TB
  • Maximum filesystem size (ext3): 16TB
  • Maximum per-process virtual address space: N/A

Please note that above are standard maximum limitations and do not get confused with Linux cluster systems, which can scale up to 1,024 CPUS.

For up-to-date information always refer to Linux kernel documentation located at /usr/src/linux/Documentation.

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9 comments… add one
  • Mace Moneta Feb 13, 2008 @ 3:05

    These limitations are for the “vanilla” (out-of-the-box) Linux system. The values can be tweaked, and single system images up to 1024 dual core CPUs (not clustered) with 4TB RAM, have been created as of last August. Those patches are available as required by the GPL, if you want to run your own large scale system.

  • Jake Feb 16, 2008 @ 16:23

    Darn…how am I supposed to do anything with only 64 processors? :-

  • jeremi g Apr 9, 2008 @ 6:29

    i do not believe any of these statistics are correct, and i’d like to see your sources.

    1. vanilla x86 kernel alone can support 255 cpus, not sure about x86-64 at the moment. there are also patches available to support up to 4096 cpus on a single kernel without clustering.

    2. maximum filesize is totally dependent upon the filesystem, just as filesystem size is. linux can support files up to 8 exabytes in size with xfs.

    3. x86-64 can support 16 exabytes of RAM, not 128G. we have systems at work running redhat and suse with 32 engineering samples of 8G FBDIMMs (that’s 256G of ram)

  • Ceder Apr 21, 2008 @ 5:26

    And what about the desktop capacity system with ths X86 32-64 Processor?

  • Michael M May 24, 2008 @ 4:08

    Remember way back in the day when it was said “who would ever need more than 16 cores in their pc” 😉

  • :) Nov 4, 2009 @ 23:19

    Proves *NIX is far superior than Windows 😉

  • (: Nov 16, 2009 @ 20:57

    Windows is another architecture different than that of UNIX. Most of the other commenly used os’es are based on Unix. But Windows is entirely different than unix .
    Total number of processor support is not only to measure the superiority. Windows kernel can also tweaked to support more CPU cores if needed.

    • :] Jun 1, 2010 @ 17:55

      For a nominal fee, of course.***

      ***Restrictions may apply. Max amount of CPU’s will remain the same. Microsoft holds the right to control any core it sees fit.

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