The range of scanned LUN IDs for an ESXi host can be from 0 to 16,383. ESXi ignores LUN IDs greater than 16,383. The configurable Disk.MaxLUN parameter controls the range of scanned LUN ID range. The parameter has a default value of 1024.

The Disk.MaxLUN parameter also determines how many LUNs the SCSI scan code attempts to discover using individual INQUIRY commands if the SCSI target does not support direct discovery using REPORT_LUNS.

You can modify the Disk.MaxLUN parameter depending on your needs. For example, if your environment has a smaller number of storage devices with LUN IDs from 1 through 100, set the value to 101. As a result, you can improve device discovery speed on targets that do not support REPORT_LUNS. Lowering the value can shorten the rescan time and boot time. However, the time to rescan storage devices might also depend on other factors, including the type of the storage system and the load on the storage system.

In other cases, you might need to increase the value if your environment uses LUN IDs that are greater than 1023.


  1. Click Manage in the VMware Host Client inventory and click Advanced Settings.
  2. Scroll down to Disk.MaxLUN.
  3. Right-click Disk.MaxLUN, and click Edit option.
  4. Enter a new value and click Save.
    The SCSI scan code does not scan the LUNs with IDs greater than or equal to the value you enter.
    For example, to discover LUN IDs from 0 to 100, set Disk.MaxLUN to 101.