Veeam backup of Vmware VSAN explained

[its-user01]

Veeam backup ntfs using blocks.
VMware VSAN is not block storage, so can anyone explain how Veeam backup process is working, when backing up vm´s on VSAN?

[Egor Yakovlev]

Hi Brian,
We are backing up VMs which reside on vSAN storage. For those VMs we will use Virtual Appliance transport mode to read data, which essentially will be mounting protected VM disks to Veeam Proxy virtual machine(residing on same vSAN). Veeam will do block reads on mounted VMDK and use native VMware CBT(Changed Blocks Tracking) to perform incremental backups.
Full read on how it works can be found here.
/Thanks!

[its-user01]

We already use Veeam to backup our VSAN enviroment, but we do not use Virtual Appliance Mode but Network Mode. So how does it work when using Network Mode?

[Andreas Neufert]

Hi, it is explained here: https://helpcenter.veeam.com/docs/backu ... l?ver=95u4 just some lines under the above sent link.
Here is a VMware explanation: https://pubs.vmware.com/vsphere-50/inde ... t.5.5.html

[its-user01]

I am looking for an step by step explanation how the backup process works, when backing up vm´s on VMware vSAN.

From when the backup of one vm starts to it is saved on Veeam backup repository.

[Andreas Neufert]

Can you please explain what step do you miss at the documentation?
https://helpcenter.veeam.com/docs/backu ... l?ver=95u4

For vSAN there is nothing special at the NBD mode by design of VMware.

[its-user01]

I am interested in seeing how blocks are moving between Veeam server and ESXi server. The link only explain the overall process. I need the nerd explanation;)

[Egor Yakovlev]

I doubt there is a possibility to go deeper than VDDK API calls used in the process? Maybe VMware engineers can help with more details.
/Cheers!

[Andreas Neufert]

There is a data connection port (TCP 902) on the ESXi hosts. We identify the VM over vcenter which point us to the ESXi that the VM is actually running on. We ask vCenter for the changed blocks and then open the data connection to the ESXi host and read from a specific vmdk the data blocks as we need. The protocol used for this is called NFC. You can basically directly access any file on the ESXi host and datastores through that data connection and work with them directly. In this case reading a specifc amount of data at specific offsets. It is similar to a video application reading data from a big video file that was palced on a network share.

Then the proxy do deduplication, compression and potentially encryption and store it at the Repository within our backup file format.

[Andreas Neufert]

Ah, please let me add, that the ESXi host itself is reading data from the vSAN backend. This is out of our control. Basically the read process from the backend is done in the same way as the ESXi host would run the VM and read/write data.

[mriksman]

There is a data connection port (TCP 902) on the ESXi hosts. We identify the VM over vcenter which point us to the ESXi that the VM is actually running on. We ask vCenter for the changed blocks and then open the data connection to the ESXi host and read from a specific vmdk the data blocks as we need. The protocol used for this is called NFC. You can basically directly access any file on the ESXi host and datastores through that data connection and work with them directly. In this case reading a specifc amount of data at specific offsets. It is similar to a video application reading data from a big video file that was palced on a network share.

Then the proxy do deduplication, compression and potentially encryption and store it at the Repository within our backup file format.

So if the connection between VBR and vCenter is down, backups and restores do not work?

[Andreas Neufert]

If you add the VMware environment by vCenter, you need by default at backup and restore the vcenter as we manage and authenticate us through it.

But in an emergency (restore) situation you can add any ESXi host to Veeam by IP address and perform restores as long as your storage (in this case vSAN) can be accessed.