[kovesp]

Originally Posted by chaley

First note: CC does not support directly accessing OTG storage. Exception: if the storage is "mounted" (somehow, often requires root) in the file system so any app can see it.

As for the list of possible storage locations for a format (a book in PDF, EPUB, or some other form): when CC fetches a book via one of the connections it stores that book in the location specified for the format of that book. Are you suggesting that the book might exist in more than one location? Would the locations have different versions of the file? Or alternatively, are you suggesting that some files of a given format are stored in location A and others are stored in location B but never both A and B? If the latter, what is supposed to happen if a format is in location A but location A is not available? What happens when the book is deleted from CC and the "right" storage is not available?

My "feeling" is that you want the CC database to contain a lot of books where the book files are stored in different removable storage locations. For example, you might have "fiction" on SD card A and have "academic" papers on SD card B. If SD card A is inserted then CC can launch reader apps on "fiction", but launching the app it will fail for "academic". If SD card B is inserted then the inverse happens; CC can launch reader apps for "academic" but not "fiction". Does this approximate what you want to do? If so, why do you want to do this? Do you have more to store than can fit on a single SD card?

FWIW: if the above is a reasonable approximation of what you want then you can it today. Set CC's storage folder to the SD card, then be sure that the "right" SD card is inserted when you download books to CC. One problem: CC doesn't bother to verify that the format actually exists before launching the reader app, an oversight I should fix. Another problem: the "Books with missing files" could do rather severe damage to the database if the "wrong" SD card (or no SD card) is inserted.

for your reply.

• OTG. It is directly supported with drives mounted as /storage/UsbDriveA, etc., without root on both my Note 3 and Note Pro 12.2. This even works perfectly with a 1 TiB external drive (assuming I also supply external power to the drive). Don't know whether this a Samsung extension or a feature of Lollipop, it also used to work on KitKat.
  As an aside, it is also possible to use Total Commander with a plugin by Paragon to R/W access NTFS drives and R/O access HFS drives without root, though this does not create a mount point so CC cannot access it.
• My request is related to the way I use CC, which is perhaps not in a way you may envisioned.
  
  I do not use it at all to maintain book libraries on my devices. I use it only as a convenient way to download (transfer) books wirelessly. In the current setup I have AZW and MOBI pointed at the location used by the Kindle app and I have PDF pointed at the location used by the ezPDFReader app. I use CC to get the books and then I go to either of the other apps to read them.
  
  The main use I would make of the mechanism I asked for is this. When I am at home and want a book on my Kindle Voyage reader, I connect up the Kindle to my Windows PC and used Calibre to transfer books to it. But I can't do that when I am not at home. So currently all I can do is
  • Use Amazon's almost useless 'Experimental Browser' to access the web interface exposed from my NAS ... very tedious;
  • Use the standard Kindle location on the phone/tablet, download with CC, connect the Kindle then copy or move;
  • Connect the Kindle, change the CC location to it, donwload, change the location back.
  The requested feature would automate everything. Just connect up the Kindle, the primary location (under /storage/UsbDriveA) now exists, CC downloads to it, eject the Kindle. The next download from CC will automatically go to the right place on the phone/tablet.