Avamar: During image backup snapshot operations, a 256KB Windows Snapshot Partition is created on EFI/GPT virtual disks
Summary: During image backup snapshot operations, a 256KB Windows Snapshot Partition is created on EFI/GPT virtual disks.
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Symptoms
During an Avamar VM image backup of Windows 2008 R2 and windows 2012 R2 EFI GPT virtual machines, additional Windows Snapshot Partition may be created with size of 256Kb after the image backup snapshot operation is complete.
These partitions can be observed using the "Disk Management" tool which reports an additional partition of an unknown file system on GPT disks with a size of 0mb.
These partitions can be observed using the "Disk Management" tool which reports an additional partition of an unknown file system on GPT disks with a size of 0mb.
Cause
This issue occurs when the IOCTL operation is used. Disk Management tools report an additional partition of the type UNKNOWN on GPT disks. It is a 256 KB snapshot partition and used in the restore process.
See VMware article 2055296 Quiesced snapshot of a Windows 2008, 2012 R2 using GPT creates a ghost partition
Resolution
The additional partition of the type UNKNOWN on GPT disks is an expected behavior and can be safely ignored.
Additional Information
In older Avamar proxy releases, the unknown GPT partition causes FLR mount to fail with "Failed to determine the partition type," but in Avamar 7.5.1 and later the FLR workflows should ignore these partitions type.
Affected Products
AvamarProducts
Avamar, Avamar Client for VMwareArticle Properties
Article Number: 000057324
Article Type: Solution
Last Modified: 07 Oct 2025
Version: 4
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