Note: Scratch space is configured automatically during installation or first boot of an ESXi host, and is not required to be manually configured. During installation, ESXi creates a 4 GB FAT16 partition on the target device if there is sufficient space, and if the device is considered Local. A /scratch symlink is then created in the root directory which points to the 4 GB partition. The default value of ScratchConfig.CurrentScratchLocation is the partition that /scratch symlink points to.
For more information, see Creating a persistent scratch location for ESXi 4.x/5.x/6.x (1033696).
Install an Emulex iSCSI driver version later than 11.2.x. The driver is available through the Customer Connect portal.
For more information on the setting and creating a persistent scratch location, see ScratchConfig.CurrentScratchLocation is set to /scratch after upgrading to ESXi 6.x (2151209)
Note: Ensure every ESXi host has a uniquely named directory on the storage.