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Disable PAE in ESX Server 2.x Guest Operating Systems for Better Performance (2020)


I have one (or both) of the following configurations:
  • A bigmem kernel installed on my Linux guest operating system.
  • The /PAE switch enabled in boot.ini on my Windows guest operating system.
Is PAE required in the guest operating system?


Physical Address Extension (PAE) allows memory addresses greater than 4GB (up to 64GB) on Intel 32-bit architectures. ESX Server is capable of addressing memory over 4GB. ESX Server 2.x guest operating systems, however, can address a maximum of only 3.6GB of memory. Therefore, PAE is unnecessary in guest operating systems.

Bigmem kernels in Linux have PAE extensions. Linux installations for SMP virtual machines may install bigmem kernels.

Although ESX Server 2.x virtual machines are compatible with PAE, they are not optimized for it. As a result, guest operating systems with PAE enabled may experience poor performance. For best performance, we recommend you disable PAE in guest operating systems.

To disable PAE:

  • On Linux guests, install the non-bigmem kernel.
  • On Windows guests, remove the /PAE switch in boot.ini. For more information, see the Microsoft knowledge base article at


2020; urlz

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