Modern servers does not have anymore ant cdrom drive, and virtualization has made these peripherals even useless. Why do we would have to have it, if every installation is done using the .ISO files directly loaded in some datastore?
The only left use case is the hypervisor installation, the only “bare metal” component of the infrastructure. But there are even in this case many alternatives.
The first that comes to mind is having an external usb cdrom drive: every bios is able to boot from here. Problems are the need to carry it with us every time and to burn everytime the last ESXi release.
Even without a cdrom drive, on many servers you can use the management card (iLO, DRAC or others) and connect the .ISO remotely, but often this feature is not available in the standard version of these cards and you need to buy additional licenses to do so.
There is a third way, that is to use a USB key to install ESXi. You only need a small USB key (I tested a 2 Gb one, but I think you can use a smaller one also) and the ESXi ISO file.
First of all, download unetbootin. It’s available for Windows, Linux or Mac so you can run it from your preferred OS.
Format the USB key using FAT or FAT32 filesystem and leave it connected to your computer.
The program can create automatically bootable USBs for many Linux distributions, or it allows to choose an ISO file.
So select your VMware ESXi ISO file:
If you connected and formatted the USB key before running the program, it will find the key and suggest you to use it. Otherwise, close unetbootin, insert the key and relaunch the program:
Click OK and wait for the write operations to complete. If you are updating an already used key, the program will tell you ubninit is already present, accept to overwrite it.
When the write is complete, close unetbootin and use the key.
With is you will be albe to run the ESXi installer on any server directly using the USB key. This method is also handy to easily update your own installer media to a desired ESXi version, without bringing around many cdrom but only using the ISO that we all usually have with us.