CBT client using 500+ GB disk space

I am new to urbackup, trying to find a replacement for Windows Server Essential bare metal backup. Urbackup seems to be generally working well for me. I purchased a license for the CBT client to test the speed beginning using a single machine. Again this worked great.

However, I have a huge issue with the disk space occupied by the CBT client application v2.4.10 on Windows. I find that after 12 hours of running, the application uses over 500 GB of disk space, occupying more than half of my OS system SSD and more than double the dataset on the drive. Digging in the program directory, I found a file named “hdat_file_e.dat” which accounts for 99% of the problem (502 GB in size).

I do have two spinning hard drives attached to this machine but they were excluded from both the image and the file backup. In the settings, image backup is set to “C” under “Volumes to backup.” Also under “Add/Remove backup path” only the “C:” drive is listed. However, I did NOT specifically exclude the E: and F: drives in the settings under “Exclude from backup” because they is not part of the backup path in the first place.

I would appreciate some help as in this form the program is not usable. Given that I am a noob with this, I assume I am doing something stupid.

Under the suspicion that the hdat_file_* may be related to change block tracking, I set change block tracking globally to volume C only in the advanced settings on the server. I uninstalled the client and removed the client backup from the server to start over. However, upon reinstallation of the client, the CBT info shows

Volumes with active change block tracking and no crash persistence (v2.16): F:, E:, C:

So limiting change block tracking to Volume C did not seem to have worked. The setting seems to have transferred to the settings.cfg file on the client, which includes the line “cbt_volumes_def=C”. What am I doing wrong here.

Sorry about, I’ll improve it such that it only uses as much hash data as is necessary for the files backed up from the disk… You can delete those files while the client is stopped (no need to uninstall).

That just means the driver is still active for the volumes. It cannot be removed without rebooting the system. The hash files shouldn’t be re-created at that point, though.

Thank you for the response, and no need to apologize. I am glad that these files can be removed without installing and removing the backup files on the server. This will greatly speed up testing.

I did abort the last backup and reboot the machine. Even after reboot, drives C, E, and F are still listed with active CBT in the CBT Status window. However, I have not seen any hdat files for drives E and F yet. Are you saying that even if the driver is active for the excluded drives, the hdat* files will not be created?

To close the issue, after limiting CBT to the C drive, the large hdat files for the E and F drives have not returned. I conclude that urbackup is working properly, just the message in the CBT status window on the client is somewhat misleading.