Latest revision: 2020-10-08
To enhance critical notification to our customers using our VMware vCenter/ESXi backup solution, a VMware version check feature on each backup job has been added, as there is a known VMware Changed Block Tracking (CBT) bug which exists on the following versions of VMware vCenter/ESXi:
This known VMware CBT bug can sometimes return incorrect changed sectors on a guest virtual machine during a VMware backup. As the CBT is used by the CloudBacko Pro for VDDK backup modes, it affects the integrity of both incremental and differential backups.
If a VMware VDDK mode backup is performed on any of the affected versions (i.e. v5.0, v5.1, v5.5 and v6.0), even if the VMware vCenter/ESXi was subsequently upgraded to a later version, CloudBacko Pro will not be able to restore the guest VMs due to the known VMware CBT bug, even though all backup jobs are recorded as successful by the CloudBacko Pro. Furthermore, as it is a VMware bug, the CloudBacko Pro Periodic Data Integrity Check (PDIC) and Data Integrity Check (DIC) will not be able to detect this issue.
As part of the backup job, CloudBacko Pro v4.1.4 (or above) will check the current VMware version to identify if it is affected by the CBT bug. If the VMware version detected is related to the affected version (i.e. v5.0, v5.1, v5.5 and v6.0), then CloudBacko Pro will show a warning in the Backup Report indicating that the VMware host is affected by the CBT bug.
Below is a sample of backup report for a VMware ESXi 5.1.0 host with the affected version:
The warning message will also indicate the VMware version or build no. which contains the fix for the CBT issue:
VMware ESXi 5.1.0 build-1157734 is the current problematic version. The following patch needs to be applied: FixedBuildNo: 2323236.
|Current backup source includes ESXi server(s) which could sometimes return incorrect changed sectors (KB2090639). Please upgrade the following ESXi server(s) to the fixed build to avoid backup incorrect backup data: [Name:localhost.localdomain (VMware ESXi 5.1.0 build-1157734), FixedBuildNo:2323236]. Reference: VMware ESXi 5.0.x, 5.1.x and 5.5.x (https://kb.vmware.com/s/article/2090639) and VMware ESXi 6.0.x (https://kb.vmware.com/s/article/2136854)|
To resolve this problem, it is strongly recommended to perform the following:
Although CloudBacko v4 (or above) no longer supports the creation of new VMware backup set for VMware vCenter/ESXi v5.0 and v5.1, backup sets which are upgraded from the previous versions are still supported with the following workaround: