Sometimes you need to hide some disks in order to protect them from possible usage. This operation is called LUN masking (at host side), and before vSphere 6.0, was also recommended before un-presenting a LUN (at storage side) to avoid the All-Paths-Down (APD) condition. Starting with ESXi 6.0 is now possible; just unmount the datastore.
For more information, see KB 1009449—Masking a LUN from ESX and ESXi using the MASK_PATH plug-in (https://kb.vmware.com/kb/1009449). Also note that vCenter automatically hides some LUNs; all that are already mounted or used as RDM disk, but only for hosts or VM managed by the same vCenter.
You can control this behavior using those vCenter Server advanced settings:
|
Advanced parameter |
Description |
|
Config.vpxd.filter.vmfsFilter |
When it's set to false, it allows you to add a VMFS volume to a VM even when in use by another VM |
|
Config.vpxd.filter.rdmfilter |
When it's set to false, it allows you to add a LUN to a VM, as Raw Device Mapping (RDM), even when the LUN is used by another VM |
|
Config.vpxd.filter.SameHostandTransportsFilter |
When set to false, incompatible LUNs are allowed to be added as extents |
|
Config.vpxd.filter.hostRescanFilter |
When set to false, the auto rescan for all hosts is disabled after adding storage |