Host Side Linking for VMware Virtual Machines

The VMware VM Storage pattern (VirtualMachinesStorage from the VMware.VMStorage module) provides Host-Side Linking (HSL) functionality for virtual machines running on VMware ESX/ESXi hosts. It covers scenarios where customers cannot directly scan virtual hosts but still need visibility into storage resources provided to virtual machines (VMs). The pattern discovers and creates virtual disk drives for each VM, establishing relationships between VMs and their underlying physical storage infrastructure, including physical disk drives and storage volumes.

The pattern's key capabilities include:

• Creating a DiskDrive node for each VM disk.
• Linking virtual disks to physical storage devices (Disk Drives or Storage Volumes).
• Supporting regular virtual disks and Raw Device Mapping (RDM) disks.
• Handling thin provisioning attributes (thin_provisioned attribute for Disk Drive).
• Managing input/output (IO) allocation limits (io_allocation_limit attribute for DiskDrive).
• Providing datastore relationship mapping (datastore_name attribute for DiskDrive).
• Automatic cleanup of virtual disk drives when VMs are removed.

Before you begin

To discover storage devices by using the VMware VM Storage pattern, ensure that the pattern is enabled in the configuration section before running a scan.

Software pattern summary

The following table gives an overview of the pattern characteristics:

Attribute	Value
Pattern Name	VirtualMachinesStorage and VMStorageRemoval
Module	VMware.VMStorage
Category	Storage
Publishers	VMware
Products	Virtual Machine File System (VMFS), Virtual Disk, Virtual Machine

Supported disk types

The following table shows the VMware VM Storage disk types and their associated components that can be discovered and modeled:

Disk type	Component
VMware Mapped RawLUN (RDM)	Direct Logical Unit Number (LUN) access Physical compatibility mode Raw Device Mapping disks Virtual compatibility mode
VMware Virtual Disk	Standard virtual disks backed by VMFS datastores Supports thin or thick provisioning Various disk modes (persistent, independent, etc.)

Trigger conditions

The main pattern VirtualMachinesStorage is triggered by VMware ESX/ESXi hosts (os_type matches VMware ESXi), provided that access through vCenter or vSphere is available. The pattern processes only hosts with running VMs.

The removal pattern VMStorageRemoval is triggered by virtual hosts (serial starts with VMware- or model starts with VMware). Virtual disk drives are cleaned up only when VMs are removed.

Software instance type attributes

The Virtual Disk Drive attributes are as follows:

Attribute	Description
key	Unique identifier (disk.key/vm.key).
name	Device label or generated name.
type	VMware Virtual Disk or VMware Mapped RawLUN.
size	Disk capacity in bytes.
vendor	VMware.
model	Virtual Disk.
virtual	True.
compatibility_mode	Virtual or Physical (for RDM).
thin_provisioned	True or False.
disk_mode	persistent, independent_persistent, etc.
file_name	Virtual Machine Disk (VMDK) file path.
uuid	Disk UUID.
datastore_name	Backing datastore name.
io_allocation_limit	I/O throttling limit.

Discovery run process

The VMware VM Storage pattern discovers and models storage devices through the following steps:

1. The VMware VM Storage pattern verifies that HSL for VMs functionality is enabled and validates that the required access method (vCenter/vSphere) is available.
2. The pattern searches for running VMs on the ESX/ESXi host, skipping any VMs that contain virtual hosts to prevent duplication.
3. The pattern maps ESX datastores to filesystem objects and creates lookup tables to manage datastore relationships.
4. The pattern queries the VM device configuration through the vSphere API, retrieving disk properties, such as capacity (bytes/KB), device labels, backing store information, provisioning type, IO allocation limits, and compatibility modes.
5. For each VM disk, the pattern creates a DiskDrive node, sets the appropriate attributes based on disk type, and establishes a containment relationship with the VM.
6. The pattern links virtual disks to their backing storage volumes (for RDM), connects virtual disks to datastore storage devices, and uses NAA (Network Address Authority) ID extraction for accurate volume identification.

Relationship creation

The pattern establishes the following relationship model:

Virtual Machine
     |
     | (Containment)
     v
Disk Drive (virtual)
     |
     | (StorageUse)
     v
Physical Storage:
- Disk Drive (physical) 
- Storage Volume
- Datastore/FileSystem

Limitations

No known limitations.

Troubleshooting

The following troubleshooting steps address common issues that might occur during VMware VM storage discovery and provide recommended resolutions.

Issue symptom A

No virtual disks are created.

Resolution

1. Check hsl_on_vm_enabled configuration.
2. Verify vCenter/vSphere access method.
3. Confirm that VMs are running and accessible.

Issue symptom B

Storage linking failures.

Resolution

1. Verify that storage volume discovery is working.
2. Check NAA ID format in logs.
3. Ensure that datastore relationships are established.

Issue symptom C

RDM disk issues.

Resolution

1. Verify LUN UUID format.
2. Check storage array discovery.
3. Confirm RDM compatibility mode.

Key log messages for monitoring

• Creating virtual Disk Drive(s) on VM - the start of the disk discovery process for a VM.
• Failed to get devices for VM - unable to retrieve the list of devices attached to the VM.
• HSL for VMs functionality is disabled - the HSL feature for VMs is not enabled in the configuration.
• No running Virtual Machines found - no active VMs on the host.
• Not able to get NAA ID using lun_uuid - could not extract the NAA identifier from the LUN UUIDs.