CBT disabled for proxy VM

[perjonsson1960]

Folks,

We have 22 MS SQL servers being backed up using Application Aware. In the logs for one (1) of the servers I suddenly saw this (in bold):

-------------------------------
Using backup proxy VeeamProxy-02a.dir1.local for disk Hard disk 1 [hotadd]
Using backup proxy VeeamProxy-02c.dir1.local for disk Hard disk 2 [hotadd]
Using backup proxy VeeamProxy-02b.dir1.local for disk Hard disk 3 [hotadd]
Using backup proxy VeeamProxy-02a.dir1.local for disk Hard disk 4 [hotadd]
Using backup proxy VeeamProxy-02c.dir1.local for disk Hard disk 5 [hotadd]
Changed block tracking has been disabled for backup proxy VM
Changed block tracking has been disabled for backup proxy VM
Changed block tracking has been disabled for backup proxy VM
Hard disk 3 (200 GB) 44 GB read at 147 MB/s [CBT]
Hard disk 2 (170 GB) 4,7 GB read at 293 MB/s [CBT]
Hard disk 1 (120 GB) 5,1 GB read at 150 MB/s [CBT]
Hard disk 5 (50 GB) 0 B read at 0 KB/s [CBT]
Hard disk 4 (1020 GB) 70,5 GB read at 108 MB/s [CBT]
Removing VM snapshot
---------------------------------

Since it says [CBT} at the end of the hard disk log lines, I assume that CBT has been used. I have never seen this in any logs before. The same proxy servers are used for other VMs, and this message is not shown in those logs.

Edit: We are using B&R 12.0.0.1420 P20230718.

Kind regards,
PJ

[Mildur]

Hi PJ

It's noted in the user guide:
https://helpcenter.veeam.com/docs/backu ... ml?ver=120

NOTE
If you back up a VM to which the backup proxy role is assigned and that uses Virtual appliance (HotAdd) transport mode, CBT for this VM is disabled and cannot be enabled.

It's strange that those disks are still showing [CBT]. CBT shouldn't be used for the disks of such proxies.
It could be a bug. I tried to backup a hotadd proxy in my 12.1.1.56 lab and it shows me the disabled message, but [CBT] is not displayed after the disk.

I suggest to upgrade to V12.1.1.56 and try again. If you still see the [CBT] displayed after the disks, then please open a case.

Best,
Fabian

[perjonsson1960]

It is not the backup proxy server that is being backed up. I am sorry if I was unclear. The VM being backed up in this case is named "edu29", and it does not have the backup proxy role. Our backup proxies are not used for anything else, and they are not backed up.

[Andreas Neufert]

CBT behind the disk is added when we use CBT for backup. If the Proxy VM has CBT enabled or not does not matter.

The issue is if you backup proxy VMs while there are HotAdd backups, CBT is a mess.

For the message in the logs about CBT disabled on the Proxy. Likely VBR or any other backup tool backed up this server and enabled it automatically, not knowing that it is a hotadd proxy used in another job.

[perjonsson1960]

It is not the backup proxy server that is being backed up. I am sorry if I was unclear. The VM being backed up in this case is named "edu29", and it does not have the backup proxy role. Our backup proxies are not used for anything else, and they are not backed up.

[perjonsson1960]

The message "Changed block tracking has been disabled for backup proxy VM" did <u>not</u> appear during the latest backup session.
Previously I had chosen certain backup proxies and guest interaction proxies to be used in the jobs, but now I have changed it to Automatic Selection, and let B&R decide which proxies to use. I don't know if that has any impact on this, but still...

[Andreas Neufert]

If I understand the above in total correctly, then we detected that for a Proxy VM the CBT was enabled or re-enabled and we disabled CBT for them. You see below that the disks from the other VMs are backed up with CBT, so everything is normal.

Additional runs on the same proxy listed will not show the "disabling CBT" message anymore, as it was already disabled as it should be.
So everything looks in order.

[perjonsson1960]

Thanks!

PJ