[DoctorOhh]

Originally Posted by chaley

The On Device column shows information for the device currently plugged in and recognized by Calibre. When you unplug the device, the information is removed. It doesn't care that you might have another device waiting to be plugged in or what that device is. For example, my wife and I each have a Sony Pocket. When I plug mine in, Calibre shows me ondevice information for the books on my reader, and when I plug hers in, I see that information for hers.

This answered my main question.

Originally Posted by chaley

You might be thinking that the information is persistent, retained when the device is unplugged. It isn't.

I see below you are caching the metadata on the devices themselves.

Originally Posted by chaley

If you want Calibre to remember what is on a device, then you must store that info yourself. To solve this problem (keep track of what is on each device when the device isn't plugged in), I created two Yes/No columns, one named CB (for me) and one DT (for my wife). The last thing I do before unplugging a reader (assume mine) after adding/deleting books is: 1) clear CB to empty using the bulk metadata editor, 2) search for books on the device (search ondevice:true), then 3) select all these books and set CB to Yes using the bulk metadata editor.

Thanks for the idea.

Originally Posted by chaley

If you look at the device's storage using a file explorer, you might notice a file '.metadata.calibre'. Calibre stores metadata for the books in this file. Please don't edit it. If you delete the file, Calibre will rebuild it from scratch the next time Calibre recognizes the device, which could take a long time.

Yes you answered my question(s). Thanks!