I've been using Dell Backup and Recovery on my XPS18 since I bought it. It has worked through Windows 7, Windows 8.1 but now no longer works in Windows 10 for some reason.
I'm using the same external WD drive I bought with the XPS18. The drive is connected directly to the USB 3.0 port on the XPS18. It is a 1TB My Passport WDBACX001088K-1. Backups used to take about 3 hours.
When I first upgraded to Windows 10, I was informed that there is a new version of Dell Backup and Recovery. So I upgraded it to the latest version, and it installed properly.
I was then warned that since I now have Windows 10, I should do a full System Backup, so I did that and this is where the problems began.
It asked me if I wanted to Delete my Windows 8 backups to free up space, which I did. Then, when I start the System Backup, it does the steps... Create list of files to be backed up.. it finishes, although it takes a while to do it, then when it starts the backup it takes FOREVER to get to 29% and then just fails. I mean it takes about 18 hours to get to that point. I have tried this three times. On the last attempt, I turned off my Carbonite backup and my Trend Micro, turned off the screen saver and set the power settings to stay on indefinitely, and the same thing still happens: Gets to about 29% and stops with a very simple message saying "backup failed", with an OK button. (It might say something a little more than "backup failed" but it is a short sentence with no error codes or reasons for failure)
My XPS18 hard drive is a 500GB drive and it is full up to 421GB. Post processing, I noticed that there is PLENTY of disk space on the WD MY Passport with over 800GB on it.
So in short, Dell Backup and Recovery has been working for me for years now, but after upgrading to Windows 10 and getting the newest version of Backup and Recovery, the backup operates extremely slowly and when getting to about 29%, it just fails with no error code or reason message.