Changed block tracking enabled but not working

Question

I was validating VM backups and assumed that our vmguests running at hardware v7 with change block enabled would automatically work. I just noticed in the backup log the following message that leads me to beleive there is a problem or parameters are not specified: here is the text of the output: 22:05:20 avvcbimage Info <9677>: changed block list dump.. 2011-03-15 22:05:20 avvcbimage Info <9678>: changed block origin:0 length:42949672960 2011-03-15 22:05:20 avvcbimage Info <9679>: end of changed block list 2011-03-15 22:05:20 avvcbimage Info <9683>: changed block list unavailable or entire disk changed, performing full level zero backup I see this message in numerous vm guest backups.

Luis_Rogerio · Answer

Hi,

Maybe this link help you https://solutions.emc.com/emcsolutionview.asp?id=esg110720

Cause

There is a known issue in the default configuration of the VMware Image Dataset for Avamar 5.0.0-407, 5.0.0-409 and 5.0.0-410 that prevents Avamar from using VMware Change Block Tracking to perform incremental backups of VMware virtual disks
The utilize_change_block_list option is not set by default in this dataset, forcing full backups each time

Resolution

There are two settings that affect the use of change block tracking. Follow the instructions below to verify change block tracking is correctly enabled for each client (Item 1) and for the VMware Image Backup Dataset (Item 2).

Verify that the "Enable change block tracking" is set in the policy settings for each affected client:
1. In the Avamar Administrator GUI, open the Policy panel.
2. Select the "Clients" tab above the tree on the left.
3. Select an affected client in the right-hand pane, then click the Edit button.
4. Select the "VMware" tab.
5. If "Enable change block tracking" is not checked, check it.
6. Click "OK" to save the settings.
7. Repeat steps 3 through 6 for any other affected clients.
Adjust the settings of the default VMware Image Dataset to utilize the changed block list:
1. In the Avamar Administrator GUI, select Tools => Manage Datasets... from the menu bar.
2. Select the VMware Image Dataset in the tree on the left.
3. Click "Edit" to edit the dataset.
4. Select the "Options" tab.
5. In the "Select Plug-In Type" dropdown menu, select "Windows VMware Image".
6. Verify that "Use change block tracking to increase performance" is checked.
7. Click "OK" to save the settings.
8. Two "utilize_changed_block_list=true" entries should appear in the Options section of the dataset editor - one for the Linux plug-in and one for the Windows plug-in.
9. Click "OK" to save your changes.

This issue was corrected in Avamar Server version 5.0.1-32.

Note: After enabling change block tracking, one additional full backup will be run to generate a change block list. Subsequent backups should run as incremental backups.

Disclaimer: Please update the customer server to Eureka SP3 immediately. There numerous enhancements to VMware Image backup. Version 5.0.x should not be used.

I hope this help.

Regards

Luis Rogerio

ICI · Answer

I am having this exact problem with Avamar 5.0.3-29, but the change block settings are properly set in both the dataset, and the client. Does anyone have any other ideas? I can see from the log file that change tracking = true, so it does seem to recognize that the settings are there and valid yet I still get the

"changed block list unavailable or entire disk changed, performing full level zero backup"

These are seen in the log file so I have to assume that the flags are properly being passed...

changeBlockDetectionEnabled="true" vmxPath="[iSCSI-PROD01]

Thanks

dstarm · Answer

I opened a case with EMC support. i have yet to actively work with them due to other internal issues and timing. however the support tech did respond in an email as follows:

confirm after enabling Changed block tracking ( CBT) if you have power cycle the Virtual Machine to confirm CTK files are created.

This Issue has been fixed in Eureka SP3 - 5.0.3-29.

We do have CBT enabled and have not had the opportunity to recycle any VM guest systems at this time. I hope to validate over the weekend.

Debbie

jbldt73 · Answer

Did EMC resolve this?

Avamar

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