You can format a USB flash drive to boot the ESXi installation or upgrade.

These instructions assume that you are performing the procedure on a Linux machine and that the USB flash drive is detected by the operating system as /dev/sdb.


The ks file containing the installation script cannot be located on the same USB flash drive that you are using to boot the installation or upgrade.

From the VMware Web site, download the ESXi ISO image VMware-VMvisor-Installer-5.x.x-XXXXXX.x86_64.iso, including the file isolinux.cfg,where 5.x.x is the version of ESXi you are installing, and XXXXXX is the build number of the installer ISO image.

Verify that the machine opn which you are performing this procedure has access to syslinux version 3.86. This procedure requires syslinux version 3.86.


If your USB flash drive is not detected as /dev/sdb, or you are not sure how your USB flash drive is detected, determine how it is detected.


In a terminal window, run the following command.

tail -f /var/log/messages

This command displays current log messages in the terminal window.


Plug in your USB flash drive.

The terminal window displays several messages identifying the USB flash drive, in a format similar to the following message.

Oct 25 13:25:23 ubuntu kernel: [  712.447080] sd 3:0:0:0: [sdb] Attached SCSI removable disk

In this example, "[sdb]" identifies the USB device. If your device is identified differently, use that identification, without the brackets, in place of sdb, in this procedure.


Create a partition table on the USB flash device.

/sbin/fdisk /dev/sdb


Type d to delete partitions until they are all deleted.


Type n to create primary partition 1 that extends over the entire disk.


Type t to set the type to an appropriate setting for the FAT32 file system, such as c.


Type a to set the active flag on partition 1.


Type p to print the partition table.

The result should be similar to the following text:

Disk /dev/sdb: 2004 MB, 2004877312 bytes
255 heads, 63 sectors/track, 243 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1             1           243      1951866  c   W95 FAT32 (LBA)

Type w to write the partition table and quit.


Format the USB flash drive with the Fat32 file system.

/sbin/mkfs.vfat -F 32 -n USB /dev/sdb1


Run the following commands.

/path_to_syslinux-3.86_directory/syslinux-3.86/bin/syslinux /dev/sdb1
cat /path_to_syslinux-3.86_directory/syslinux-3.86/usr/share/syslinux/mbr.bin > /dev/sdb

Mount the USB flash drive.

mount /dev/sdb1 /usbdisk


Mount the ESXi installer ISO image.

mount -o loop VMware-VMvisor-Installer-5.x.x-XXXXXX.x86_64.iso /esxi_cdrom


Copy the contents of the ISO image to /usbdisk.

cp -r /esxi_cdrom/* /usbdisk


Rename the isolinux.cfg file to syslinux.cfg.

mv /usbdisk/isolinux.cfg /usbdisk/syslinux.cfg


In the file /usbdisk/syslinux.cfg, change the line APPEND -c boot.cfg to APPEND -c boot.cfg -p 1.


Unmount the USB flash drive.

umount /usbdisk


Unmount the installer ISO image.

umount /esxi_cdrom

The USB flash drive can now boot the ESXi installer.