For new installations of ESXi, during the autoconfiguration phase, a scratch partition is created as part of the ESX-OSDATA partition.

Note: Partitioning for hosts that are upgraded to ESXi 7.0 and later from earlier versions differs significantly from partitioning for new installations of ESXi. The upgrade process to ESXi 7.0 and later repartitions the boot device and consolidates the original core dump, locker, and scratch partitions into the ESX-OSData volume.

The scratch partition serves to store system logs, which you need when you create a support bundle. If the scratch partition is not present, system logs are stored in a ramdisk. If no scratch partition is created, you can configure one. You can also override the default configuration.

You can create the scratch partition on a remote SAN or NFS-mounted directory.