Scratch Partition is used to store logs of ESXi
Installing ESXi requires a boot device that is minimum 1GB in size. To create the VMFS volume and scratch partition, the ESXi installer requires a minimum of 5.2GB of free space on the installation disk. If a smaller disk or LUN is used, the installer attempts to allocate a scratch region on a separate local disk. If a local disk cannot be found, the scratch partition (/scratch) is located on the ESXi host ramdisk, linked to /tmp/scratch
You can reconfigure /scratch to use a separate disk or LUN.
When installing ESXi onto a USB flash drive or SD flash card, if the drive is less than 8 GB, this prevents the allocation of a scratch partition onto the flash device. VMware recommends using a retail purchased USB flash drive of 16 GB or larger so that the “extra” flash cells can prolong the life of the boot media but high quality parts of 4 GB or larger are sufficient to hold the extended coredump partition.
Due to the I/O sensitivity of USB and SD devices, the installer does not create a scratch partition on these devices. When installing on USB or SD devices, the installer attempts to allocate a scratch region on an available local disk or datastore. If no local disk or datastore is found, /scratch is placed on the ramdisk. You should reconfigure /scratch to use a persistent datastore following the installation.
In Auto Deploy installations, the installer attempts to allocate a scratch region on an available local disk or datastore. If no local disk or datastore is found, the /scratch directory is placed on ramdisk. Reconfigure the /scratch directory to use a persistent datastore following the installation.
For environments that boot from a SAN or use Auto Deploy, it is not necessary to allocate a separate LUN for each ESXi host. You can co-locate the scratch regions for many ESXi hosts onto a single LUN. The number of hosts assigned to any single LUN should be weighed against the LUN size and the I/O behavior of the virtual machines
ESXi selects one of these scratch locations during startup in order of preference:
The location configured in the /etc/vmware/locker.conf configuration file, set by the ScratchConfig.ConfiguredScratchLocation configuration option
A Fat16 filesystem of at least 4 GB on the Local Boot device. with local boot device I mean local disk or SAN/iSCSI LUN
A Fat16 filesystem of at least 4 GB on a Local device.
A VMFS Datastore on a Local device, in a .locker/ directory.
A ramdisk at /tmp/scratch/
For hosts where a scratch partition hasn’t been automatically created, the following steps can be followed:
Select the ESXi host in the inventory.
Click the Configuration tab.
Click Storage.
Right-click a datastore and select Browse.
Create a uniquely-named directory for this ESXi host (eg, .locker-ESXHostname)
Close the Datastore Browser.
Click Advanced Settings under Software.
Select the ScratchConfig section.
Change the ScratchConfig.ConfiguredScrathLocation configuration option, specifying the full path to the directory (this needs to be unique for every ESXi host). For example:/vmfs/volumes/DatastoreName/.locker-ESXHostname
Put the ESXi host in maintenance mode and reboot for the configuration change to take effect.
===============
Please do share your Thoughts about this Post. Thank-you for reading
Happy Learning