[DMcCunney]

Originally Posted by BetterRed

@DMcCunney - How big is your library?

99+ GB

I am not trying to use Calibre as a general purpose library and indexing utility, though I'm aware I could.

The stuff indexed by Calibre is all essentially text in one format or another.

My initial reaction to splitting a library into multiples based on format and the capacity of backup thumb drives is - no, no, don't do that!!

I prefer to use good quality hard disks for backup rather than thumb drives - 2TB drives in a USB 3 disk dock. My calibre libraries consume ~700GB (one them has lots of large files - video, audio and image collections), the non calibre data is ~400GB. I use something similar to FFS to do the backups called Goodsynch.

The point to the USB thumbdrive is less backup than portability. Calibre is installed on the machines that travel, too, and when I travel, the Calibre library can travel with me.

Yes, there are portable HDs. But those are mostly spinning platter devices, and things with moving parts break. I've had one old low capacity USB thumbdrive fail on me, and they are cheap and getting cheaper. (The 128GB USB3 thumbdrive that currently holds the backup Calibre library instance cost about $16. Storage is down to under ten cents a GB and dropping. I'm probably getting another 128GB thumbdrive and duplicating the current Calibre drive as a "belt and suspenders" move.)

Cloud is another option - I believe Amazon gives unlimited storage for US$60pa. My line speeds are too slow to consider using cloud storage for anything other than casual use.

I have a 100mbit/sec cable connection with 20mbit/sec upload, but I'm not at the point of using the cloud for backup.

Have you considered using Calibre Companion on your Android devices. It interoperates with desktop calibre and it can access a calibre library kept in Dropbox and OneDrive accounts - not sure about Amazon.

I have it installed on the tablet. The problem I have is that it can't do what I originally wanted. What I was looking for was an Android utility that could tell me what all I had on my tablet's microSD card using the metadata Calibre deposits there without invoking my eBook viewer.

It appears CC can do that sort of thing, but only for volumes transferred via Wifi. I have thousands of volumes on the tablet transferred via USB cable, and I really don't want to redo everything just to use CC.

I'm not especially interested in keeping this sort of thing on Dropbox or OneDrive. I make increasing use of Google Drive for stuff I want access to from anywhere, but that tends to be stuff I want to provide access to to others as well because we are collaborating on the projects the stuff is for.

My use of multiple libraries relates to custom columns and how I use standard columns. I have three 'permanent' libraries - Main, Media and Journals.

My Main library (~85K books) has 6 custom columns, my Media library (~12K books) has 26 custom columns, and my Journals library (~6K books) has the Journal Name in the Author column and the Journal Issue No/Date in Title column and 11 custom columns. All three libraries have a number of Virtual Libraries and book list Views (View Manager plugin).

I tried combining them into into a single library, and contriving schemes to partition the Virtual Libraries and Views. But I found it far too cumbersome with limited benefit, so I reverted to multiple libraries.

In your use case, I'd do the same. I have about 20K volumes all told, and no present need to rice, slice, and dice them as you do.

I use X1 or Windows Search for content searching. In the context of calibre I use the Drop Search Results and Reading List PIs to store the search results.

I'm still thinking about content searching. I dual boot Windows and Linux, so I'd want equivalent functionality available from either OS.

Back when, I ran Google Desktop under Windows as a content searching tool, because it could open and index content in archives with the right plugins. Finding files isn't a problem. Finding specific information in files is another matter. (In the old days, it was all text and I'd just use grep. No longer...)

I bridge the libraries via links from calibre Books and Authors to Evernote Notes, and via Chrome shortcuts from Evernote Notes to calibre server Author and Book URLs. I would do this irrespective of the number of libraries.

I don't use Evernote or Chrome. (I may get to Evernote at some point. I vastly prefer Firefox to Chrome.)

If you want to get a single top level list of what's in all three of your libraries, how do you do it?
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Dennis