Backup Support for Dynamic Disks and GPT (in VDDK and VCB)

Products

• VMware vSphere ESXi

Issue/Introduction

This article describes VMware support in VDDK (Virtual Disk Development Kit) and VCB (VMware Consolidated Backup) for file-level backup of virtual machines that have:

• Virtual disk configured to use Dynamic Disks within the guest operating system
• Virtual disk configured with GUID Partition Table (GPT) in the guest operating system

Symptoms:

What backup support does VMware offer for dynamic disk and GPT?

Environment

VMware Consolidated Backup 1.0.x
VMware Consolidated Backup 1.5.x
VMware Consolidated Backup 1.1.x
VMware Virtual Disk Development 1.2

Resolution

The following points apply to file-level backup of Windows virtual machines using VDDK 1.2.1 and earlier releases, or VCB version 1.5 Update 1 and earlier releases. For backups on ESX/ESXi hosts, VDDK is associated with vSphere APIs for Data Protection (VADP).

• VDDK and VCB support dynamic disks, unless a disk reports "Missing" status within disk management.
• VCB does not support file-level backup of virtual machines if the system folder is on dynamic disk.
• Neither VDDK nor VCB support RAID-5 dynamic disk, which cannot be mounted on the backup proxy.
• VDDK and VCB have not been tested with GPT, which is unsupported for both.
• VDDK has some hooks for Logical Volume Manager (LVM) disks on Linux.

Note: If disk management shows a missing dynamic disk, it means that a dynamic disk attached to the system cannot be located. The missing disk shows up in disk management because every dynamic disk in the system has knowledge about other dynamic disks.

If a virtual disk configured as dynamic disk within the guest is marked independent, the file-level mount will not be able to mount any volumes. Because independent disks are not part of a snapshot, when VDDK or VCB checks the dynamic disk database on the proxy, it finds that some of the dynamic disks are missing, hence the failure.

Additional Information

See http://support.microsoft.com/kb/816307 for more information about dynamic disks.

See Wikipedia for information about GPT.

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