Determining the boot device type and size for each ESXi host in the workload domain is important for the creation of system storage volumes. You also plan the location of the scratch partition according to the selected boot device type so that system log information is available even if a storage failure occurs.
ESXi requires a boot disk of at least 8 GB for USB or SD devices, and 32 GB for other device types such as HDD, SSD, or NVMe. A boot device must not be shared between ESXi hosts.
ESXi can boot from a disk larger than 2 TB if the system firmware and the firmware on any add-in card support it. See vendor documentation.
The ESXi system storage volumes occupy up to 128 GB of disk space. A local VMFS datastore is only created if the local disk device has at least 4 GB additional free space. To share a boot device with a local VMFS datastore, you must use a local disk of 240 GB or larger. If a local disk cannot be found, ESXi operates in a mode with limitations, where certain functionality is disabled, and the scratch partition is on the RAM disk of the ESXi host, linked to the /tmp folder. As a result, log information and stack traces are lost on host reboot. You can reconfigure the scratch partition to use a separate disk or LUN.
Decision ID |
Design Decision |
Design Justification |
Design Implication |
---|---|---|---|
SDDC-WLD-VI-ESXi-004 |
Install and configure all ESXi hosts in the shared edge and workload cluster to boot using a 32-GB device or greater. |
Provides hosts with large memory, that is, greater than 512 GB, with enough space for the core dump partition while using vSAN. |
When you use SATA-DOM or SD devices, scratch partition and ESXi logs are not retained locally. Configure the scratch partition of each ESXi host on supplemental storage. |
SDDC-WLD-VI-ESXi-005 |
Use the default configuration for the scratch partition on all ESXi hosts in the shared edge and workload cluster |
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When you use SATA-DOM or SD devices, scratch partition and ESXi logs are not retained locally. Configure the scratch partition of each ESXi host on supplemental storage. |