Is it relatively safe to put calibre portable in Dropbox and launch in 2 computers?

Quuzuu · 12-17-2020, 11:56 PM

I'm not trying to set up some fancy workflow, what I do is very basic - I put my portable calibre folder (containing the Library folder) in my Dropbox, then I may launch it from either my laptop PC or my desktop PC, which will show the same library.

My use of calibre is also very basic - drag books in, convert, edit metadata, etc.

My question is, do I need to be very careful and always make sure calibre is closed on one computer before launching on another computer? My optimistic assumption is that the database of every book is be standalone, and having 2 calibres running won't cause any trouble unless I open the "edit" window of the same book simultaneously and overwrite each other when hitting "ok" - which I won't do, but even if I did it's not a huge deal.

What I absolutely don't want is to somehow corrupt the whole library. Is there a chance that could happen?

pdurrant · 12-18-2020, 03:32 AM

Do not have two instances editing a single database. Calibre hasn't been designed or tested for that situation, and the most likely result is a corrupt database somewhere along the line.

BetterRed · 12-18-2020, 05:26 AM

Quote:

Originally Posted by Quuzuu

I'm not trying to set up some fancy workflow, what I do is very basic - I put my portable calibre folder (containing the Library folder) in my Dropbox, then I may launch it from either my laptop PC or my desktop PC, which will show the same library.

My use of calibre is also very basic - drag books in, convert, edit metadata, etc.

My question is, do I need to be very careful and always make sure calibre is closed on one computer before launching on another computer? My optimistic assumption is that the database of every book is be standalone, and having 2 calibres running won't cause any trouble unless I open the "edit" window of the same book simultaneously and overwrite each other when hitting "ok" - which I won't do, but even if I did it's not a huge deal.

What I absolutely don't want is to somehow corrupt the whole library. Is there a chance that could happen?

Your optimistic assumption is wrong, calibre does not maintain a separate database for every book, it maintains a separate database for every library.

The metadata.db file in the library directory is an SQLite database that contains tables for books, authors, tags etc - one row in the books table is one book, ditto authors, tags etc.

The scenario you describe is likely to lead to a corrupt database. The metadata.opf files you see in the book folders are there to restore the database if it gets corrupted by misuse.

In almost a decade of using calibre, on several libraries, one with 180,000+ 'books', I have never had to restore a library database.

BR

Sirtel · 12-18-2020, 07:21 AM

I have my Calibre library in Dropbox and am using it on 3 laptops. Yes, you can only have 1 instance running at the same time. Moreover, pause syncing while Calibre is open. Always sync BEFORE opening Calibre and AFTER closing it. Ditto for your other computer. And even taking those precautions conflicted copies still happen. Which means you have to run the library maintenance regularly.

For me, the setup is worth the bother. But I'm certainly in a tiny minority with this.

Quuzuu · 12-18-2020, 01:04 PM

Quote:

Originally Posted by Sirtel

I have my Calibre library in Dropbox and am using it on 3 laptops. Yes, you can only have 1 instance running at the same time. Moreover, pause syncing while Calibre is open. Always sync BEFORE opening Calibre and AFTER closing it. Ditto for your other computer. And even taking those precautions conflicted copies still happen. Which means you have to run the library maintenance regularly.

For me, the setup is worth the bother. But I'm certainly in a tiny minority with this.

Hi, do you have any experience of deviating from this strict practice and had consequences? What was the consequences?

ownedbycats · 12-18-2020, 01:23 PM

I wouldn't risk it, but if you want to try anyways I'd disable Dropbox auto-syncing while it's open. And keep lots of library backups.

Sirtel · 12-18-2020, 02:00 PM

Quote:

Originally Posted by Quuzuu

Hi, do you have any experience of deviating from this strict practice and had consequences? What was the consequences?

I have forgotten to sync before or after using Calibre a few times, and opened my library on another computer. Dropbox immediately generated a conflicted copy of the database file, and sometimes also several book files. Luckily I'm in the habit of checking the integrity of my library often, and so caught the errors before things escalated.

ownedbycats · 12-18-2020, 02:39 PM

A safer alternative might be to run Calibre portable from a secondary folder, and use your choice of tools to run a manual sync to the Dropbox folder at the beginning and ending of your Calibre session. Depending on what software you use, it may be possible to automate this to some extent.

That way the changes propagate between computers, but you aren't running it inside Dropbox and risking the real-time sync fudging with things.

12-17-2020, 11:56 PM	#1
Quuzuu Member Posts: 11 Karma: 10 Join Date: Dec 2020 Device: Kindle iOS App	Is it relatively safe to put calibre portable in Dropbox and launch in 2 computers? I'm not trying to set up some fancy workflow, what I do is very basic - I put my portable calibre folder (containing the Library folder) in my Dropbox, then I may launch it from either my laptop PC or my desktop PC, which will show the same library. My use of calibre is also very basic - drag books in, convert, edit metadata, etc. My question is, do I need to be very careful and always make sure calibre is closed on one computer before launching on another computer? My optimistic assumption is that the database of every book is be standalone, and having 2 calibres running won't cause any trouble unless I open the "edit" window of the same book simultaneously and overwrite each other when hitting "ok" - which I won't do, but even if I did it's not a huge deal. What I absolutely don't want is to somehow corrupt the whole library. Is there a chance that could happen?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Unable to run Calibre portable from Dropbox	tools44	Devices	11	08-11-2014 07:33 PM
Calibre Portable and Dropbox	anleva	Related Tools	11	10-24-2012 12:30 PM
Using one Calibre Library (via Dropbox) on Multiple Computers	PocketGoddess	Related Tools	14	02-20-2011 04:15 AM
[Q] Calibre settings sync between computers using dropbox	Dopedangel	Related Tools	8	12-21-2010 07:44 AM
Calibre & Dropbox and 2 computers????	jekoby	Related Tools	3	08-02-2010 03:16 AM

12-18-2020, 03:32 AM	#2
pdurrant The Grand Mouse 高貴的老鼠 Posts: 73,903 Karma: 315160596 Join Date: Jul 2007 Location: Norfolk, England Device: Kindle Oasis	Do not have two instances editing a single database. Calibre hasn't been designed or tested for that situation, and the most likely result is a corrupt database somewhere along the line.

12-18-2020, 07:21 AM	#4
Sirtel Grand Sorcerer Posts: 13,432 Karma: 238916691 Join Date: Jan 2014 Location: Estonia Device: Kobo Sage & Libra 2	I have my Calibre library in Dropbox and am using it on 3 laptops. Yes, you can only have 1 instance running at the same time. Moreover, pause syncing while Calibre is open. Always sync BEFORE opening Calibre and AFTER closing it. Ditto for your other computer. And even taking those precautions conflicted copies still happen. Which means you have to run the library maintenance regularly. For me, the setup is worth the bother. But I'm certainly in a tiny minority with this.

12-18-2020, 01:23 PM	#6
ownedbycats Custom User Title Posts: 10,919 Karma: 74203799 Join Date: Oct 2018 Location: Canada Device: Kobo Libra H2O, formerly Aura HD	I wouldn't risk it, but if you want to try anyways I'd disable Dropbox auto-syncing while it's open. And keep lots of library backups.

12-18-2020, 02:39 PM	#8
ownedbycats Custom User Title Posts: 10,919 Karma: 74203799 Join Date: Oct 2018 Location: Canada Device: Kobo Libra H2O, formerly Aura HD	A safer alternative might be to run Calibre portable from a secondary folder, and use your choice of tools to run a manual sync to the Dropbox folder at the beginning and ending of your Calibre session. Depending on what software you use, it may be possible to automate this to some extent. That way the changes propagate between computers, but you aren't running it inside Dropbox and risking the real-time sync fudging with things.

Advert

Advert