Home > Storage > PowerVault > Guides > Dell PowerVault ME5 Series: VMware vSphere Best Practices > Missing LUN Response
The setting for Missing LUN Response is in PowerVault Manager under Settings > System > Properties > Cache Properties.
The default setting of Illegal Request is compatible with a VMware vSphere environment and should not be changed. Some operating systems do not look beyond LUN 0 if they do not find a LUN 0, or cannot work with noncontiguous LUNs. This parameter addresses these situations by enabling the host drivers to continue probing for LUNs until they reach the LUN to which they have access. This parameter controls the SCSI sense data returned for volumes that are not accessible because they do not exist or have been hidden through volume mapping.
In a vSphere environment, ESXi interprets the Not Ready reply as a temporary condition. If a LUN is removed from an ESXi host without properly unmounting the datastore first, and if the missing LUN response is set to Not Ready, ESXi may continue to query for this LUN indefinitely.