Error: Snapshot size is multiplied in vm.storageAllocationMb event property in VMware Cloud Director 10.6.1.2

Products

• VMware Cloud Director

Issue/Introduction

VMware Cloud Director event logs report incorrect values for the vm.storageAllocationMb property when multiple snapshots exist on a Virtual Machine (VM). The reported size reflects a multiplication of the first snapshot size by the total number of snapshots rather than the cumulative total.

Symptoms:

• vm.storageAllocationMb values increase exponentially with each new snapshot.
• Storage metrics in events do not match the vCloud Director UI.
• Manual billing discrepancies occur for cloud service providers.

Verification Example:

1. The first snapshot was created without memory, with a size of 62.18 GB.

From the VCD event data, we observed:

• VM was powered on (vm.state = 1)
• vm.storageAllocationMb = 299242 MB = 292.22 GB
• vm.storageProfile.name.VSAN = 235565 MB = 230.04 GB

Therefore, snapshot size = 292.22 GB − 230.04 GB = 62.18 GB

This snapshot size matches the total snapshot size shown in the vCloud Director UI. 

2. The second snapshot was created with memory, with a size of 10.26 GB.

From the data, we observed:

• VM was powered on
• vm.storageAllocationMb = 362919 MB = 354.41 GB
• vm.storageProfile.name.VSAN = 235565 MB = 230.04 GB

Therefore, snapshot size = 354.41 GB − 230.04 GB = 124.37 GB

This snapshot size does not match the total snapshot size shown in the vCloud Director UI. Ideally, the storageAllocationMb should have reflected: 230.04 GB (VSAN) + 62.18 GB (1st snapshot) + 10.26 GB (2nd snapshot) = 302.48 GB.

It is believed that the resulting 124.37 GB is actually the size of the first snapshot (62.18 GB) multiplied by the number of snapshots at that point in time (2), i.e., 62.18 × 2 = 124.37 GB.

3. The third snapshot was created with memory, with a size of 8.01 GB.

From the data, we observed:

• VM was powered on (vm.state = 1)
• vm.storageAllocationMb = 426596 MB = 416.59 GB
• vm.storageProfile.name.VSAN = 235565 MB = 230.04 GB

Therefore, snapshot size = 416.59 GB − 230.04 GB = 186.55 GB

This snapshot size also does not match the total snapshot size shown in the vCloud Director UI. Ideally, the storageAllocationMb should have reflected: 230.04 GB (VSAN) + 62.18 GB (1st snapshot) + 10.26 GB (2nd snapshot) + 8.01 GB (3rd snapshot) = 310.49 GB.

Analysis suggest that the resulting 186.55 GB is, similarly, the size of the first snapshot (62.18 GB) multiplied by the number of snapshots at that point (3), i.e., 62.18 × 3 = 186.55 GB.

Environment

VMware Cloud Director 10.6.1.2

Cause

This caused due to a code-level defect in the composite key implementation within VmSnapshotStorageClassMetricsView preventing correct tracking of snapshot storage size.

Resolution

The issue is resolved in VMware Cloud Director 10.6.2.

To resolve this issue, upgrade to VMware Cloud Director 10.6.2 or higher. Refer Download Broadcom products, patches and software to download this release.

Workaround: Perform manual billing for end-clients by verifying snapshot sizes directly in the vCloud Director UI until the upgrade is completed.