ESXi hosts can boot from an iSCSI SAN using the software or dependent hardware iSCSI adapters and network adapters.

To deploy ESXi and boot from the iSCSI SAN, the host must have an iSCSI boot capable network adapter. The adapter must support the iSCSI Boot Firmware Table (iBFT) format, a method of communicating parameters about the iSCSI boot device to an operating system.

Before installing ESXi and booting from the iSCSI SAN, configure the networking and iSCSI boot parameters on the network adapter. Because configuring the network adapter is vendor-specific, review your vendor documentation for instructions.

When you boot from iSCSI for the first time, the iSCSI boot firmware on your system connects to an iSCSI target. If a login is successful, the firmware saves the networking and iSCSI boot parameters in the iBFT and stores the table in the system's memory. The system uses this table to configure its own iSCSI connection and networking and to start up.

The following list describes the iBFT iSCSI boot sequence.
  1. When restarted, the system BIOS detects the iSCSI boot firmware on the network adapter.
  2. The iSCSI boot firmware uses the preconfigured boot parameters to connect with the specified iSCSI target.
  3. After the successful connection, the iSCSI boot firmware writes the networking and iSCSI boot parameters in to the iBFT. The firmware stores the table in the system memory.
    Note: The system uses this table to configure its own iSCSI connection and networking and to start up.
  4. The BIOS boots the boot device.
  5. The VMkernel starts loading and takes over the boot operation.
  6. Using the boot parameters from the iBFT, the VMkernel connects to the iSCSI target.
  7. After the iSCSI connection is established, the system boots.