Boot option to configure the size of ESXi system partitions
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Boot option to configure the size of ESXi system partitions


Article ID: 345195


Updated On:


VMware vSphere ESXi


ESXi 7.0 introduced a system-storage boot media layout designed to ensure new features and capabilities could be added in future releases. The partition layout can consume up to 138GB of disk space, which limits the usable space to create a VMFS datastore on a small server with finite hardware resources.

ESXi 7.0 Update 1c  release adds the boot option systemMediaSize to customize the space used by system-storage during installation and better match the purpose and size of the server.


VMware vSphere ESXi 7.0.0


With ESXi 7.0 Update 1c System storage consumes a default of 138GB if systemMediaSize is not provided. It is the recommended size for most servers. Fore more information refer to ESXi 7.0 Update1c release notes

The systemMediaSize boot option accepts the following parameters with the corresponding size used for ESXi system partitions:
  • min     33GB, for single disk or embedded servers
  • small   69GB, for servers with at least 512GB RAM
  • max     all available space, for multi-terabyte servers
Note: GB units specified are in storage device sizes, i.e. 1,000,000,000 byte multiples
Boot options can be provided to the installer in various ways depending on what install method is used (refer to the links in the Related Information section for more detail). There are two methods below for providing the boot option at startup and apply to any chosen installer media.

Entering the boot option at boot media startup:

  • Start the host with the install image and when the ESXi installer window appears, press Shift+O within 5 seconds to edit the boot options.
For example, add the following prompt:

Modifying boot.cfg to have the boot option:

Edit the boot.cfg file in the install image and add the boot options to the kernelopt line.

For example, kernelopt=runweasel systemMediaSize=small

Additional Information

ESXi 7.0 requirements for boot media  
Entering boot options during installation
Creating a custom ISO image for installation
ESXi installer bootable media choices