Created attachment 141911 [details]
Snapshot of two disks merging in Nemo

SUMMARY
There is some room for improvement on the way that Dolphin handles large/multiple copy queues.

Please, allow me to illustrate with a few scenarios.
 
Scenario 1: Merging two external USB drives into one.

Imagine two external USB drives that are 1Tb each, the content of which is to be merged on to a 2Tb USB drive.
As each copy operation takes 3 to 4 hours, I would like to have the first copy operation run on it's own, and the second copy operation start once the first is finished. This enables a person to set up a copy queue and go to bed, with the merged disk waiting in the morning.  
Dolphin simply has no functionality for this, and instead insists on running the copying in parallel, thrashing the heads on the receiving disk, and apart from the horrible wear and tear makes it take much, much longer. 

Just how difficult is it to enable one copy process to wait for another to be finished? Are these copy processes not aware of each other? Would it really be so hard to just append more files to be copied on to the end of the first copy queue?

Scenario 2:

Copying 100k+ files from various sources into one collection. 
When squirreling away large digital collections of anything, there are invariably files that have weird names, are corrupted, or the media they are sitting on is corrupt, or a network link drops out at the wrong time, or an act of God stops a file from being copied. 

It would be wonderful if Dolphin would automatically bump that file to the end of the copy queue and carry on with the files it can copy. Some copy processes do take a long, long time and one does not want to baby-sit a computer when there are more productive things to be done. 

The user can then decide what to do about the troublesome files when the trouble files are all that is left of the copy queue: Retry All, Abort, Retry Single, Skip Single, Delete Destination, and so on... It would be super-handy here to be able to panelize the copy queue at this point, and step through the trouble files until you either give up or there are none left. 

These scenarios are admittedly not very common for all users, but for the types of user that do find themselves shifting around large amounts of old data, this is a very handy feature. I have used Supercopier on other platforms, and once you have used it, you tend to miss the functionality when it's not available. 

In my case, I installed Nemo on my KDE desktop, just because I can now let these disks merge nice and sequentially while I get some sleep.