Maximum Memory and CPU Limitations for Linux Server

last updated in Categories Linux

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.


Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

9 comment

  1. 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.

  2. 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)

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

  4. 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.

    1. 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.

    Have a question? Post it on our forum!