VMFS Datastores missing from new hosts that were added to an existing cluster.

Products

• VMware vSphere ESXi

Issue/Introduction

New hosts added to an existing cluster do not see the same set of datastores as the other hosts in the cluster. 
The LUNs have been mapped accurately from the storage array to these hosts.

Environment

VMware vSphere 7.0
VMware vSphere 8.0
FC and iSCSI

Cause

 

In this scenario, it is due to LUNs presented with a LUN ID greater than 1024 from the storage array, even though the total number of LUNs presented to the host are not exceeding 1024. 

From VMware configuration maximums:  
Maximum number of fiber Channel - SCSI  LUNs per host  = 1024
Maximum number of fiber Channel - SCSI LUN ID              = 0 to 16383

 

In ESXi 7.0.x and 8.0.x default value of Disk.MaxLUN is set at 1024. 
The value of Disk.MaxLUN also determines how many LUNs the SCSI scan code attempts to discover using individual INQUIRY commands

Resolution

In order to use LUN IDs greater than 1024 while keeping the total number of LUNs presented to less than 1024, change the Disk.MaxLUN value to a desired value less than or equal to 16383. 

Select the host in the cluster > Configure Tab > Advanced System Settings  > Edit  > Disk.MaxLUN. 

Make the change on all the required hosts.