ESXi 7.0 introduces a system storage layout that allows flexible partition management and support for large modules, and third-party components, while facilitating debugging.

ESXi 7.0 System Storage Changes

Before ESXi 7.0 , partition sizes were fixed, except for the /scratch partition and the optional VMFS datastore, and the partition numbers were static, limiting partition management. With ESXi 7.0, partitions are consolidated into fewer, larger partitions that are expandable, depending on the used boot media and its capacity.

The ESXi 7.0 system storage layout consists of four partitions:
Table 1. ESXi 7.0 system storage partitions:
Partition Use Type
System Boot Stores boot loader and EFI modules. FAT16
Boot-bank 0 System space to store ESXi boot modules. FAT16
Boot-bank 1 System space to store ESXi boot modules. FAT16

Acts as the unified location to store additional modules.

Not used for booting and virtual machines.

Consolidates the legacy /scratch partition, locker partition for VMware Tools, and core dump destinations.

Note: Must be created on high endurance storage devices.

The ESX-OSData volume is divided into two high-level categories of data, persistent and non-persistent data. Persistent data contains of data written infrequently, for example, VMware Tools ISOs, configurations, and core dumps.

Non-persistent data contains of frequently written data, for example, logs, VMFS global traces, vSAN Entry Persistence Daemon (EPD) data, vSAN traces, and real-time databases.

Figure 1. Consolidated system storage in ESXi 7.0

ESXi 7.0 System Storage Sizes

Partition sizes, except for the system boot partition, can vary depending on the size of the boot media used. If the boot media is a high-endurance one with capacity larger than 142 GB, a VMFS datastore is created automatically to store virtual machine data.

For storage media such as USB or SD devices, the ESX-OSData partition is created on a high endurance storage device such as an HDD or SSD. When a secondary high endurance storage device is not available, аn ESX-OSData volume is created on the USB or SD devices, but this partition is used only to store persistent data. Non-persistent data is stored on system memory.

You can review the boot media capacity and the automatic sizing as configured by the ESXi installer by using the vSphere Client and navigating to the Partition Details view. Alternatively, you can use ESXCLI, for example the esxcli storage filesystem list command.

Table 2. ESXi 7.0 System Storage Sizes, Depending on the Used Boot Media and Its Capacity.
Boot Media Size 4-10 GB 10-33 GB 33-138 GB >138 GB
System Boot 100 MB 100 MB 100 MB 100 MB
Boot-bank 0 500 MB 1 GB 4 GB 4 GB
Boot-bank 1 500 MB 1 GB 4 GB 4 GB
ESX-OSData remaining space remaining space remaining space up to 138 GB
VMFS datastore remaining space for media size > 142 GB
Starting with vSphere 7.0 Update 1c, you can use the ESXi installer boot option systemMediaSize to limit the size of system storage partitions on the boot media. If your system has a small footprint that does not require the maximum of 138 GB of system storage size, you can limit it to the minimum of 33 GB. The systemMediaSize parameter accepts the following values:
  • min (33 GB, for single disk or embedded servers)
  • small (69 GB, for servers with at least 512 GB of RAM)
  • default (138 GB)
  • max (consume all available space, for multi-terabyte servers)

The selected value must fit the purpose of your system. For example, a system with 1 TB of memory must use the minimum of 69 GB for system storage. To set the boot option at install time, for example systemMediaSize=small, refer to Enter Boot Options to Start an Installation or Upgrade Script. For more information, see Knowledge Base article 81166.

ESXi 7.0 System Storage Links

The sub-systems that require access to the ESXi partitions, access these partitions by using the following symbolic links:
Table 3. ESXi 7.0 system storage symbolic links.
System Storage Volume Symbolic Link
Boot-bank 0 /bootbank
Boot-bank 1 /altbootbank
Persistent data






Non-persistent data