Shulou(Shulou.com)05/31 Report--

The purpose of this article is to share with you the problem analysis of how to carry out virtual machine cbt. The editor thinks it is very practical, so I share it with you. I hope you can get something after reading this article.

Phenomenon:

"when running virtual machine backups with VMware Data Recovery (VDR), vSphere Data Protection (VDP), or any third-party backup tool running on ESXi 5.x hosts while performing incremental virtual machine backups using change Block tracking (CBT), you may experience one or all of the following symptoms:"

Virtual machine backups are larger than usual

Incremental backups require the same time and space as full backups

The snapshot deletion task failed because the backup job is still running or exceeds the backup period

Although no significant changes have been made in the virtual machine, the CBT file will grow.

Reason:

This problem occurs because CBT has been reset during virtual disk migration using Storage vMotion. This causes the backup tool to fail to recognize which blocks have changed since the last backup. Incremental virtual machine backups cannot be performed at this point, but a full backup is required.

Resolve:

This is a known issue that affects ESXi 5.0.

The issue has been resolved in the following versions:

ESXi 5.5Update 2 (available from VMware Downloads). For more information, see VMware ESXi 5.5 Update 2 Release Notes.

ESXi 5.1 Update 3 (available on VMware Downloads). For more information, see VMware ESXi 5.1 Update 3 Release Notes.

"to resolve this issue, do not use Storage vMotion or Storage DRS on the virtual machine for migration backups."

To resolve this issue on the affected virtual machine:

Shut down the virtual machine.

Remove an existing virtual machine snapshot.

Disable CBT for the virtual machine. For more information, see Enabling Changed Block Tracking (CBT) on virtual machines (1031873).

Removes or renames all files in the virtual machine directory that end with the *-ctk.vmdk file extension.

Re-enable CBT for the virtual machine.

Power on the virtual machine.

Ensure that the virtual machine is not migrated using Storage vMotion or Storage DRS.

Add:

In previous versions of VDDK, virtual machines were powered off during cold migration and resulted in loss of change Block tracking (CBT) status. "in VDDK version 5.5, if both hosts have access to both the source and destination data stores, the CBT state is retained after the virtual machine is cold migrated."

In addition, it can be achieved through scripting, as follows:

$vm= "Name"

$vmtest = Get-vm $vm | get-view

$vmConfigSpec = New-Object VMware.Vim.VirtualMachineConfigSpec

$vmConfigSpec.changeTrackingEnabled = $true

$vmtest.reconfigVM ($vmConfigSpec)

$snap=New-Snapshot $vm-Name "Enable CBT"

$snap | Remove-Snapshot-confirm:$false

The above is how to analyze the problem of virtual machine cbt. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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