Knowledge Base

This happens when the value of Disk.MaskLUNs is not delimited by quotation marks ("). To properly mask LUNs on your ESX Server system:

1. Identify the LUNs that you want to mask.
   
   
2. Identify all paths to the LUNs that you want to mask.
   
   
3. The LUN masking string (that is, the value of Disk.MaskLUNs) must include all paths to the LUNs that you want to mask.
   
   
4. Write the LUN masking string to the proc nodes. For example (replace the vmhba target and LUN numbers with your own values):
   
   echo "vmhba1:0:1,5,7-10;vmhba1:1:1,5,7-10" > /proc/vmware/config/Disk/MaskLUNs
   
   This masks LUNs 1, 5 and 7 through 10 on targets 0 and 1 on vmhba1. If you have a second HBA (for example, vmhba2), you must add the corresponding paths to the same LUNs. So, assuming that the target numbers are similar on vmhba2, the value would be:
   
   vmhba1:0:1,5,7-10;vmhba1:1:1,5,7-10;vmhba2:0:1,5,7-10;vmhba2:1:1,5,7-10;
   
   
5. If you want these LUN masking settings to persist across reboots, modify the Disk.MaskLUNs advanced option using one of the following methods:
   
   
   • On the management interface as root:
     
     
     1. Choose Options > Advanced Settings.
        
        
     2. Locate the option named Disk.MaskLUN.
        
        
     3. Enter the LUN masking string value as follows. Make sure only a single pair of quotation marks surrounds the LUN masking string value:
        
        "vmhba1:0:1,5,7-10;vmhba1:1:1,5,7-10"
        
        
   • On the service console as root:
     
     
     1. Using an editor of your choice (for example, vi or nano), open the file /etc/vmware/vmkconfig and locate the following line:
        
        Disk/MaskLUNs = "..."
        
        If this line does not exist, create the line and edit it so that it looks like this (notice the double set of quotation marks):
        
        Disk/MaskLUNs = ""vmhba1:0:1,5,7-10;vmhba1:1:1,5,7-10""
        
        
     2. Save and close the file.
        
        
6. Be aware of the following important notes:
   
   
   • There should be only one occurence of Disk/MaskLUNs = "..." in the /etc/vmware/vmkconfig file.
     
     
   • The LUN masking string should include all paths to all LUNs that are selected for masking.
     
     
   • When modifying the /etc/vmware/vmkconfig file, you must use the quotation marks ( " ) twice to delimit each side of the LUN masking string.
     
     
   • Using LUN masking cancels the effect of the advanced optionDisk.MaxLUNs.