This is a comment, not an answer, but the formatting's important, so please let this sit for a day, after which time it can be deleted, if I have not deleted it myself.

"Master' and 'Slave' are obsolete and misleading terms which were useful back in the days of MFM drives, but which should not be used on modern HDDs and SSDs. Let's rethink slightly:

/dev/sda1 Linux 731 MB
/dev/sda2 LVM   38.4 GB

/dev/sdb  5.1 GB you need to create a partition before use
  
/dev/sdc 10 GB you need to create a partition before use
 
/dev/sdd 11.7 GB you need to create a partition before use

Why did you use the complex and difficult LVM on the first drive instead of the standard ext4 partition?

"Master' and 'Slave' are obsolete and misleading terms which were useful back in the days of MFM drives, but which should not be used on modern HDDs and SSDs. Let's rethink slightly:

/dev/sda1 Linux 731 MB
/dev/sda2 LVM   38.4 GB

/dev/sdb  5.1 GB you need to create a partition before use  
/dev/sdc 10 GB you need to create a partition before use  
/dev/sdd 11.7 GB you need to create a partition before use  

In order to copy files to /dev/sdb , /dev/sdc . or /dev/sdd , you need to partition them, using the rules of VirtualBox, to complete the process of making them virtual disks, and then mount them in the virtual instance of Ubuntu 16.04 . Once you've done that, you can use Ubuntu's cp command to copy, or use its File Manager to drag-and-drop or select-copy-paste.