Have you ever looked at the boot disk of your enviroment and wondered what exactly do those entries represent? I am talking about :1, :2 and so forth... Have you ever wondered if your boot disk has the same number of partitions, or is the number potentially different when comparing two esxi hosts?
Let's take a look at the boot disk in this case. All your drives are listed in /dev/disks, which is a link to /vmfs/devices/disks. The way you recognize the boot disk is by looking at all the partitions of such drive. The boot disk is the only one that has so many partitions.
To understand the type of partitions that exist in the boot disk, simply use the partedUtil command. This command creates, removes and list partitions. Use the --help command to see all the options. In this case, we query the boot disk and see several partitions.
Let us start with partition 1. This 4mb partition contains the bootloader.
Partition 2 (4gbs in size) is used as the scratch partition. The output of vm-support is located there.
Partition 5 (250mb) is your bootbank. The hypervisor's image is located here.
Partition 6 (250) is your alt bootbank. This is used when upgrading esxi hosts.
Partition 7 is used for the Purple Screens of Death. It's 110mb in size.
Partition 8 is used to store the vmware tools images.
Final Note: Be aware that your boot disk could also have a vmfs partition. This happens for example when installing esxi on a sata disk (like in a lab). Not created on flash memory.