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Understanding the HCX Bulk Migration Error: Shared SCSI Bus and VM Migration

When migrating virtual machines (VMs) using HCX bulk migration (version 4.7), the following error appears:

“SCSI controller with bus sharing is used on VM-XX. Non VMware or out of date tools detected on VM-XX. HCX will attempt a graceful shutdown.”

Let’s break down what this error means and how it relates to your VM setup.

Raw Device Mappings (RDM) and Migration

Firstly, it’s essential to understand the role of Raw Device Mappings (RDM) in this scenario. RDM is a feature in VMware that allows a VM to directly access and use a storage logical unit (LUN) on the SAN. There are two modes in which RDM can operate:

  1. Physical Compatibility Mode: In this mode, VMs cannot be migrated. The VMkernel sends SCSI commands directly to the physical device. This mode is typically used for SAN snapshot or other layered applications.
  2. Virtual Compatibility Mode: VMs with RDM in this mode can be migrated. However, they are converted to VMDKs (Virtual Machine Disk File) at the destination. This mode allows for VM-level operations.

The Real Culprit: Shared SCSI Bus

The error you’re encountering is not directly related to RDM. Instead, it’s tied to the shared SCSI bus. The SCSI bus is a set of standards for connecting and transferring data between computers and peripheral devices. In a virtual environment, VMs can be configured to use a shared SCSI bus, which allows multiple VMs to access the same virtual disk simultaneously.

However, when it comes to migration, VMs using a shared SCSI bus pose a challenge. As per the VMware documentation:

“Virtual machines cannot be migrated while they are using a shared SCSI bus, flagged for multi-writer, enabled for fault tolerance, or configured for shared VMDK disk sharing.”

This limitation is important to understand because it directly impacts the migration process. If your VM is configured with a shared SCSI bus, it cannot be migrated until this configuration is altered.

Migration processes, especially in complex virtual environments, can be intricate. It’s essential to understand the underlying configurations of your VMs and how they impact migration capabilities. If you’re facing the aforementioned error, the solution lies in reconfiguring the VM to not use a shared SCSI bus.

For a deeper dive and more specific details on this topic, you can refer to the official VMware documentation:

Remember, a successful migration requires a thorough understanding of both the source and destination environments, as well as the tools you’re using. Always ensure you’re working with the most up-to-date information and best practices to ensure a smooth transition.

Final Note: If the information provided above doesn’t resolve your migration issues, we strongly recommend reaching out to VMware support. Their team of experts can provide a more in-depth analysis of your specific situation and guide you towards a successful resolution.

Understanding the HCX Bulk Migration Error: Shared SCSI Bus and VM Migration
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