What is the best way to keep two Calibre libraries in sync?

[Loosheesh]

Using Claude, I created a private MCP server to access my Calibre library. Although the server has no ‘write’ capabilities, I felt it was best to be safe than sorry later, so I duplicated my main library to maintain a separate library for Claude to access.

To create the duplicate library, I initially copied over the books from the main library to the MCP library. My problem right now is keeping both libraries in sync (i.e., changes made to the main library reflected in the MCP library). Additions and deletions of books are simple enough, but metadata updates are troublesome.

I use FreeFileSync to keep my Calibre libraries backed up and available both in the cloud and on a portable device, but when I tried to use it for the two libraries (main and MCP), it wanted to overwrite all the books (13K+) in the MCP library. That seemed a bit overkill.

Does anyone have suggestions for simple ways to keep both libraries in sync?

[sgmoore]

Originally Posted by Loosheesh

FreeFileSync ... wanted to overwrite all the books ...

I would probably start with trying to figure out why. The most likely suspect is the timestamps are different.

I don't use FreeFileSync, but Beyond Compare has some options to ignore daylight saving time issues and even one second differences, so FFS might have the same.
I am sure there is an option to ignore the timestamps and compare file size and file contents. That may be slower, but if your files are just normal books (and not audiobooks) it may be fast enough.

Alternatively let FreeFileSync sync a few files and see if it wants to sync them again or it it is now happy with those files. If the latter, then the problem may be a one-off and I might be easier to just let it sync all the books once.

[JSWolf]

It sounds like MCP did something to change your library. So my suggestion is to dump MCP. There is no way FreeFileSync would want to overwrite everything unless MCP changed everything.

If the fie sizes and time/date are the same, FFS will not overwrite. So MCP would have to have screwed with your library.

So get Tron to do away with Master Control Program.

[Loosheesh]

Originally Posted by sgmoore

I would probably start with trying to figure out why. The most likely suspect is the timestamps are different.

I don't use FreeFileSync, but Beyond Compare has some options to ignore daylight saving time issues and even one second differences, so FFS might have the same.
I am sure there is an option to ignore the timestamps and compare file size and file contents. That may be slower, but if your files are just normal books (and not audiobooks) it may be fast enough.

Alternatively let FreeFileSync sync a few files and see if it wants to sync them again or it it is now happy with those files. If the latter, then the problem may be a one-off and I might be easier to just let it sync all the books once.

I checked and I think it's because both the book uuids and IDs are different for the two libraries. And the book ID is appended to the folder name, so there's probably no way to get FFS to ignore that.

Now that I've run into this problem, I'm thinking I should've first copied over the entire main library folder instead of copying the books over to the new library. I might have to start over.

[Loosheesh]

Originally Posted by JSWolf

It sounds like MCP did something to change your library. So my suggestion is to dump MCP. There is no way FreeFileSync would want to overwrite everything unless MCP changed everything.

If the fie sizes and time/date are the same, FFS will not overwrite. So MCP would have to have screwed with your library.

So get Tron to do away with Master Control Program.

I have no idea what Master Control Program is

In the context I used it, MCP is Model Context Protocol

[JSWolf]

Originally Posted by Loosheesh

I have no idea what Master Control Program is

In the context I used it, MCP is Model Context Protocol

Obviously, you've never seen the Disney movie Tron. Master Control Program is the bad guy program in the computer that's been stealing other programs and making them play games.

[Loosheesh]

Originally Posted by JSWolf

Obviously, you've never seen the Disney movie Tron. Master Control Program is the bad guy program in the computer that's been stealing other programs and making them play games.

Pop culture failure on my part

[Loosheesh]

Originally Posted by Loosheesh

I should've first copied over the entire main library folder instead of copying the books over to the new library. I might have to start over.

I did start over. I got rid of the library folder I was using for the MCP server and replaced it with a full copy of my main library. All tests (with Calibre, Claude, and FFS) were successful after adding a new book. Going forward, I'll use FFS to keep the MCP library in sync with the main library.

Thanks to @sgmoore for helping me think through the problem

[PeterT]

My approach has always been to yhave ONE copy of my calibre library considered as the MASTER, where all changes are made. Other computers then receive a one way mirrored copy of that library via rclone sync.

[BetterRed]

Master Control Program was the operating system for Burroughs mainframes, there was no assembler, only Algol; Cobol, Fortran and Basic came later, MCP itself was written in a beefed-up Algol.