Cluster Change Block Tracking

Hyper-V specific discussions

[MERGED] CSV and CBT

Veeam Logoby kunniyoor » Mon Mar 30, 2015 2:00 pm

standalone Hyper-V VM's backup gives different result if the VM resides in the local disk and in the CSV volume.

For VM running from the local disk, the backup go through well with out any errors (Full or Incremental). But for the VM' s from CSV volume gives warning like " Failed to flush change tracking data. Using full scan incremental". The backup for the VM's in the CSV even it is full or incremental taking same time and amount of data to backed up.

This is same for CSV from iSCSI or FC storage.

Any clue?
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Re: Cluster Change Block Tracking

Veeam Logoby Shestakov » Mon Mar 30, 2015 2:49 pm

Hello,
Since CBT for cluster is node-based results for clusters and standalone hosts can be different.
Please read the thread for more info and ask additional questions if you have any.
Thanks!
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Re: Cluster Change Block Tracking

Veeam Logoby kunniyoor » Mon Mar 30, 2015 3:11 pm

Even we tested the CBT with clustered nodes still receiving same result "failed to flush change tracking data"
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Re: Cluster Change Block Tracking

Veeam Logoby foggy » Mon Mar 30, 2015 3:22 pm

Is there any reason for configuring CSV without a cluster? In case of CSV, changes are tracked on all cluster nodes, to avoid possibility of data loss. Since there're no more nodes, Veeam B&R lacks CBT information from them and performs full scan of VM disks to calculate changes to be transferred.
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[MERGED] Failed to create change tracking time stamp

Veeam Logoby danny@compufit.be » Thu Jun 11, 2015 1:28 pm

I have for all the backup jobs this waring

10/06/2015 21:36:38 :: Failed to create change tracking time stamp for virtual disk file C:\ClusterStorage\Volume1\Hyper-V\xxx\xxx_disk_1.vhdx

This error occures every time.

What can causes the errors and how to solved the problem?

Tnx
Dan


Support ID 00314642
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Re: Failed to create change tracking time stamp

Veeam Logoby Vitaliy S. » Thu Jun 11, 2015 1:56 pm

Hi Dan,

It's hard to say much about this error without seeing full debug log. What did our support engineer advise to do? Did you shutdown any nodes from the Hyper-v cluster by any chance?

Thanks!
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Re: Cluster Change Block Tracking

Veeam Logoby danny@compufit.be » Thu Jun 11, 2015 3:26 pm

Yes we have a node down in the cluster.
But this should not result in problems with making backups. Even with virtual machines that were not on that node.
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Re: Cluster Change Block Tracking

Veeam Logoby foggy » Mon Jun 15, 2015 2:43 pm

Actually, it does result in inability to use CBT, since, as mentioned above, CBT information is stored on nodes themselves.
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Re: Cluster Change Block Tracking

Veeam Logoby IT_Timo » Tue Jul 07, 2015 3:51 pm

Just to let Veeam know: We're also affected by this issue.

Running a five node Hyper-V Cluster we let System Center Virtual Machine Manager decide whether to turn off individual hosts based upon utilization. This Feature is called Power Optimization. Talking about buzzwords like private cloud and green IT it seems quite reasonable to activate such a feature.

Unfortunately at this time it seems we have to choose between wasting energy or exceeding the backup window and increasing system load by disabling CBT. This is not satisfying.

I already noticed that Windows Server 2016 will bring its own native implementation of CBT. Yet it will take some time until release and afterwards updating hosts. So if it's possible for Veeam to store CBT on the CSV, this might be a solution?
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Re: Cluster Change Block Tracking

Veeam Logoby Vitaliy S. » Wed Jul 08, 2015 12:18 pm

IT_Timo wrote:I already noticed that Windows Server 2016 will bring its own native implementation of CBT. Yet it will take some time until release and afterwards updating hosts. So if it's possible for Veeam to store CBT on the CSV, this might be a solution?

There were some issues with storing CBT data on the CSV storage, but, yes, that was our original implementation idea.
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[MERGED]: CBT data - new host

Veeam Logoby Cragdoo » Mon Jan 11, 2016 10:10 am

Can anyone offer an advice on how to handle the following situation.

When we add a new Hyper-V host to our cluster, and rebalance the cluster , existing VMs are moved onto the new host, however when the next backup is run a full backup is taken. I'm guessing it's because the CBT information is stored per host in HyperV , and as the VMs are moved onto the new host, no existing CBt information exists. Is there any way we can update the Veeam job to use the CBT data existing on other hosts, or am I thinking about this all wrong ?
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Re: Cluster Change Block Tracking

Veeam Logoby PTide » Mon Jan 11, 2016 11:35 am

Hi,

when the next backup is run a full backup is taken
Does that happen to all VMs or just to VMs that were moved? Also, if full read occurs that's an expected behaviour.

because the CBT information is stored per host in HyperV , and as the VMs are moved onto the new host, no existing CBT information exists.
Each host is aware of changes happened to other host's VMs. CBT data has to be cleared after VM migration thus causing full read (not full backup) during next backup run. The fact that you have full backup means that something went go wrong with VM ID. Normally Hyper-V cluster does not change VM's ID, so I suggest you to open a case with support team and post your case ID in this topic.

Thank you.
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Re: Cluster Change Block Tracking

Veeam Logoby Cragdoo » Mon Jan 11, 2016 1:42 pm 1 person likes this post

aah ..gotcha, the full read was indeed what was happening. Thanks for that
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[MERGED] Backup repository slow after addition of new Host S

Veeam Logoby Kdoel » Mon Feb 15, 2016 4:05 pm

Good Morning
On a prior evening we added an HV Host Server to a cluster. That cluster is currently being backed up in Veeam. Following the addition of the new Host Server I rescanned the Cluster to discover the new Server and install agents on it. When my backups started during the next cycle some of the backups have taken an unusually long time to complete the backups/merges. All of the slow backups are being backed up to the same repository. The Repository itself is quite healthy and shows no sign of degradation or bad disks. Do I need to rescan each repository after adding new hosts to the VEEAM B&R? Everything appears to work fine but I exceeded my SLA this morning and do not want that to occur again. Any ideas? :?
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Re: Cluster Change Block Tracking

Veeam Logoby foggy » Mon Feb 15, 2016 4:45 pm

Kevin, please review the thread above for the answer. This thread also has some further details. Thanks.
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