Which volume to clone from
 

The FTM forum has an ongoing discussion about the volume from which to clone in order to obtain the most reliable copy. The original poster said that he always cloned the volume from which he booted (his main working hard drive) and which contains the cloning software. This is my way as well. However, some experts concede that cloning the running system is eventually asking for trouble and the best way is to clone a "resting OS" from the third bootable volume that runs the cloning software. When using SD, which variant is the most reliable?

It's always "most reliable" to copy a totally inactive system from a 3rd drive. But it's sufficient, in most cases, to run from the drive you're copying from.

Thanks! This is what the consensus at FTM seems to be as well.