In new installations, several new partitions are created for the boot banks, the scratch partition, and the locker. New ESXi 5.0 installations use GUID Partition Tables (GPT) instead of MSDOS-based partitioning. The partition table is fixed as part of the binary image, and is written to the disk at the time the system is installed. Therefore we do not have any option to configure any customized partition in ESXi5.0. The ESXi installer leaves the scratch and VMFS partitions blank, and ESXi creates them when the host is rebooted for the first time after installation or upgrade. The scratch partition is 4GB. The rest of the disk is formatted as a VMFS5 partition.
ESXi5.0 was installed on 40 GB disk. From 40 GB, 4 GB is used for scratch and 4 GB for OS i.e. datastore1. It means dedicated partitions are created.
NOTE The installer can create multiple VFAT partitions. The VFAT designation does not always indicate that the partition is a scratch partition. In some cases, a VFAT partition can lie idle.
What happens to Partitioning in Upgraded ESXi 5.0 Hosts scenarios
Upgraded systems do not use GUID Partition Tables (GPT), but retain the older MSDOS-based partition label. For most ESXi 4.x hosts, the partition table is not rewritten in the upgrade to ESXi 5.0. The partition table is rewritten for systems that have lopsided bootbanks. Lopsided boot banks can occur in systems that are upgraded from ESXi 3.5 to ESXi 4.x, and then upgraded directly to ESXi 5.0. For ESX hosts, the partitioning structure is changed to resemble that of an ESXi 4.x host. The VMFS3 partition is retained and a new MSDOS-based partition table overwrites the existing partition table.
For classic ESX hosts, any data stored in custom user created partitions inside the Service Console is not preserved in the migration to ESXi 5.0.
Upgraded hosts do not have a scratch partition.
Instead, the scratch directory is created and accessed off of the VMFS volume. ESX was installed on 40 GB Disk, 4 GB is used by scratch partition and 4 GB as root partition as Storage1 VMFS as seen below.
Each of the other partitions, such as the bootbanks, locker and vmkcore are identical to that of any other system.
In upgraded hosts, the VMFS partition is not upgraded from VMFS3 to VMFS5. ESXi 5.0 is compatible with VMFS3 partitions.
You can upgrade the partition to VMFS5 after the host is upgraded to ESXi 5.0.
NOTE The ESXi 5.0 installer cannot detect ESX 2.x instances or VMFS2 datastores. You cannot migrate ESX 2.x instances to ESXi 5.0 or preserve VMFS2 datastores in an upgrade to ESXi 5.0. Instead, perform a fresh installation of ESXi 5.0.
For the VMFS partition on the disk to be preserved during an upgrade to ESXi 5.0, the partition must be physically located after the boot partition, which is partition 4, and the extended partition on the disk (8192 + 1835008 sectors). Any system that has a VMFS partition after the 1843200 sector mark can keep that VMFS partition, regardless of whether it was initially installed with ESX 3.5 or 4.x. For systems in which the VMFS partition is placed on a different drive from the boot drive, the entire contents of the boot drive is overwritten during the upgrade. Any extra data on the disk is erased.