The method I described is a really slow / time consuming process. So yes, if you really needed to backup your Tablo recordings to another drive, I suppose this would work. I use Tablo Ripper, myself, to save recordings that I want to keep.
My Tablo started acting odd a few months back ... it would record shows, but I could not schedule programs and the Live TV function stopped working. Turns out that the external HDD somehow got some bad sectors (low level stuff) on it. I had to use the technique above to copy everything recorded off of it ... and in the process I found 2 recordings that got munged up ... those files just would not copy to the other drive.
The external USB Drive I was using I had bought earlier this year, and just because it had a few bad sectors doesn't necessarily mean that it's trash. The trick to getting those bad sectors to get marked on the drive as off limits for use, is to format the drive on a PC as NTFS (I'm sure there are other ways, other operating systems that will do this too). And it has to be a full format, not the quick one ... takes several hours to complete. Once that's done, the bad sectors aught to be marked as unusable on the hard drive itself. Next step is to connect it to the Tablo, and have it format it again in the Linux format it likes. I presume that the Tablo format operation does not do the full slow sector by sector format that the PC does (but I could be wrong), but I also think that the Tablo format operation will honor the bad sector marking on the drive, and never use them.
So I did the above on that 2TB external drive, then copied all the good recordings back, and my Tablo was up and running again. Since then, I've not had any recording / playback issues, and all my old recordings, except for 2 were restored.
It would be nice, though, to have a straight-forward backup technique to use.