Strange -- Earlier you included a screen shot cbt initialised with drive d .png
that shows image backup of both D:\ and C:\ yet the above does not show that the D:\ volume has any shadow storage allocated on it, so I think that you are using the large (10GB) area on C: to hold snapshots that are taken when you are creating an image of both drives, so that means Reflect will be creating then reading the snapshot of D: from C: while at the same it is reading data blocks from D:.
You later provided a part of a log from a backup of both volumes c:\ and d:\, and it shows shadow copies for both drives being temporarily stored on the same hard disk volume, futher evidence that reflect has to involve both volumes when imaging D:\, while it also has to read both the snapshot data AND the data being backed up when imaging the C:\ volume as well as writing the image file on the F:\ volume.
If you wanted to eliminate that imbalance, you could
use vssadmin ResizeShadowStorage
option, as described in this Microsoft article
by adding a shadow storage area on D:\ and perhaps decreasing the size of the 10GB area on C:\. Or you could decide that you'd rather have all the shadow storage on C:. But you'd have to include that I/O load when trying to decide where the bottleneck is?
My thoughts are that the slowup is the disk write load on F: ? What model of drive is that and how is it attached to your system? If it is an SSD, does it use CMR or SMR recording techniques?
Edited delete the request for information already provided.
For the record, Reflect's shadow storage usage is temporary and shadow copies are removed at the end of Reflect's use of them (but System Restore Points kept in the same area are retained until deleted). But if you use just one shadow storage area to hold all snapshots, it will have to be large enough to hold BOTH snapshots while Reflect is doing the backup.
From that same screen shot, when it was taken CBT was NOT being used on the volume c:\
(the changes reflected in the MFT for C: are being used to drive the image creation for volume c:\).
The screenshots of text in ??German?? are hard for me to read -- google translate doesn't work on pictures of text.
As for having to jump thru hoops to stop the forum from interpreting some character sequences as emoticons, you can turn off the display of emoticons in the forum by clicking on your picture in the header, then Edit Account, and select Topics -- You'll find the option like this:
Again, it's your choice.
L.W. (Dan) Danz, Overland Park KS
Reflect v8.1.7847+ on Windows 11 Home 23H2 22631.3085+ | Reflect v8.1.7853+ on Windows 10 Pro 22H2 19045.3996+
Reflect v8.1.7784+ on 2 systems Windows 10 Home 22H2 19045.3803+