By default, the VMkernel scans for LUN 0 to LUN 255 for every target (a total of 256 LUNs). You can modify the Disk.MaxLUN parameter to improve LUN discovery speed.


You cannot discover LUNs with a LUN ID number that is greater than 255.

Reducing the value can shorten rescan time and boot time. However, the time to rescan LUNs might depend on other factors, including the type of storage system and whether sparse LUN support is enabled.


Browse to the host in the vSphere Web Client navigator.


Click the Manage tab, and click Settings.


Under System, click Advanced System Settings.


Under Advanced System Settings, select Disk.MaxLUN and click the Edit icon.


Change the existing value to the value of your choice, and click OK.

The value you enter specifies the LUN after the last one you want to discover.

For example, to discover LUNs from 0 through 31, set Disk.MaxLUN to 32.