CBT Functionality Question


Hello everyone,

I would like to thank you in advance for any information provided.

This is simply a question topic, to make sure that I fully understand what CBT does.
I am looking to implement it, on some clients, so I bought a test license, and I am not noticing a difference on my test machine, which is on a local Gigabit network. The image is still transferring basically the entire image for incremental.

So I am thinking I misunderstand what CBT really is.
I read and reread the FAQ on CBT and I think my understanding originally was wrong.

What I thought was that CBT calculated what is different, by blocks, and only downloaded the changes like an incremental backup does. So instead of the incremental image backup download say, 120GB it would detect 3GB has changed and only download 3GB versus the entire image.

Now after rereading it, it sounds to me like the difference calculations are precalculated on the client, and when the image is downloaded again, the server does not have to calculate these changes, lessening the load on the server itself. It does not change the fact that the incremental image basically has to download the entire image again then calculate it, server side.

What I was looking for is that, I have a few offsite machines using internet mode, and I was trying to conserve bandwidth usage by lessening the amount of data transferred.

Could someone please clarify which of these is correct, or am I entirely wrong to begin with?
Either way is fine, I just want to know before I purchase these licenses.

Thanks so much for your time!



As on the website:

Change block tracking for UrBackup Client on Windows speeds up image and file backups performed by UrBackup by tracking which blocks change between backups. Without change block tracking all data has to be read and inspected in order to find and transfer the differences during an incremental image or file backup. This can take hours compared to the same taking minutes with change block information. This enables backup strategies with hourly (or less) incremental image backups and speeds up incremental file backups with large files (e.g. virtual disks).

So, it indeed doesn’t change the amount transferred. It only avoids the client having to read all used blocks of the disk to figure out what has changed.


An answer from the man himself! Thank you so much, and I very much appreciate your work. Urbackup is an outstanding program!