CBT enabled, but not working

[globaltech]

Hello,

i'm experiencing problems with CBT on a Veeam 6.0.0.164 and ESXi 5.0 914586
In April, backups were working well.



I tried to use the HOTADD transport mode, but it disabled CBT, so I changed transport mode back to network, but no more CBT.



Then I activated CBT in the general options of the VM (was set to false). CBT now appears during a backup, but it still takes a lot of time.



What can I do to increase backup/replication performance?

Thanks

[foggy]

Most likely you are backing up the proxy server VM itself. Please note, that CBT is disabled for hotadd proxies, which could cause Veeam B&R to use its proprietary change tracking algorithm that requires reading of the entire VM disks.

[globaltech]

Thanks for the reply. Yes, there are 3 VMs and 2 of them are active proxies, but the problem happens even with the non-proxy VM. I set transport mode to Network just like it was previously, but it didn't helped. Do I have to delete the proxies and recreate them?

[veremin]

I doubt it would help, since, according to your own words, the affected VM isn’t proxy server. The possible reasons of CBT not working properly is snapshot presence, so, kindly check whether affected VM has a snapshot or not.

As to backing up proxy servers using CBT, you have to explicitly specify NBD mode and manually enable CBT on them.

Thanks.

[globaltech]

Everything is working fine now. I manually activated CBT in the VM options like explained in the VMware KB 1031873 http://kb.vmware.com/selfservice/micros ... Id=1031873

The next backup is still slow after that change, but the subsequent were OK.

[foggy]

Thanks for the update, much appreciated.