I use Windows 7 Professional x64.
Indeed, actual backups is what I prefer. I want single encrypted backup HDDs that I can store at another place than my house. To keep things simple and manageable the internal HDDs should be filled up one at a time, and the best would be not to delete content from a full drive ever again, so I can be sure that my backup drives are 100% identical to the corresponding internal drives.
The whole pooling of drives only is there for me to have a simple folder browsing experience in the Explorer and don't have to dig 3 or 4 "Videos" folders from different drives.
If I'm not mistaken, using the pool drive as the source for robocopy may not really help me in the case when 1 drive is damaged and its content is lost. I wouldn't know which content got deleted from the pool, I would only know the drive number that now is missing from the pool. And using the pool as source for robocopy doesn't guarantee that I get exact copies from my drives where HDD1 == BackupHDD1. So I would have to remember/guess which files are gone and have to search through all my backup drives for those files.
You're quite right on the budget thing. Having basically 3 copies of each file is a bit too much for me and my wallet.
I may try it out soon with those settings.
Maybe there still is hope for a tool that 'mounts' directories into the same place and merges the contents recursively.
Basically what I would need is just a tool that helps me merge 4 HDDs and its contents.
So I can have Folder X, Y, Z on the root of drive1 with some content in them.
And the same folder names X, Y, Z on the root of drive2, 3 and 4 too with content in them.
The tool should then merge the 4 drives into one, so I can access X, Y, Z and get to the content from all drives, just like a pool.
Would make things so much easier.