[Fiat_Lux]

Originally Posted by Kelpo

So, would you recommend it as a document management software?

What is your specific use-case?
* What type of documents are to be managed;
* Who uses these documents;
* How do they use them;
* When do they use them;
* Where do they use them;

If your use case includes active documents, then Calibre,in and of itself, is not suitable. In conjunction with other software, it might be suitable.

If your use case includes archiving documents, then Calibre can be used. What I do, is export the document to PDF, with a file name of Document Title YYYYMMDDHHMMSS, then import it into Calibre.
I didn't realize until today, that Calibre does not define PDF as an eBook file format. As such, I'll play with my office suite's export to ePub and export to FB2 functions, to see how well they work as document archive formats.

Is it capable of storing thousands of documents?

Yes.

Caveat # 1: Do not, under any circumstances, allow the program to automatically delete files, when running a duplicate file checking operation. You will lose your only copy of a document, if you allow "delete when duplicate file is found";

Caveat # 2: Once the library exceeds a couple of hundred books, both Calibre Server and Calibre Companion are extremely painful to use;

Caveat # 3: You will spend far more time adding, and verifying meta data, than you originally budgeted for. Yet, if you don't add/correct that metadata, you won't be able to find the document that you are looking for;

Caveat # 4: Bibliographies.
The Bibliography Export function in Calibre won't export the data in the citation format that you want. You'll have to either run a program that can convert it into the appropriate format, or hand massage it.

Recommendation # 1: Dedicate one computer to Calibre, and use it only for Calibre, or operations directly related to Calibre.

Recommendation # 2: Computer hardware:
* Have at least 4 GB of RAM for the OS, and an additional 1 GB of RAM, for every 100,000 items in your calibre library.
* Have at least three external drives:
** Drive # 1 is your working Calibre Library. The only thing on this drive is your library;
** Drive # 2 is your incremental backup library. Everytime you change something/anything in Calibre, do an incremental backup to this drive;
** Drive # 3 is your full backup library. Do a complete backup of your Calibre Library once a week;
** If budget and time allow, Drive # 4, which is your second full backup library. If you have the time, and money, implement a rotating 42 drive backup schedule;

Recommendation # 3: Calibre Libraries:
* Import Library: This is a small library, into which all content is initially imported. Metadata is then verified, and either added, or corrected, as appropriate.
* Main Working Library: All items are exported from the Import Library, to this library. This library (Main Library) is your working library, in which all content is stored;
* Supplemental Library: The optimum break size for Calibre Libraries is around 100,000 items. I budget 250 GB per 100,000 items.
Consider creating Supplemental Libraries either on a per project basis, or every 100,000 items. The downside of creating a library every "x" items, is that you have to do several searches, rather than a single search.

Is it practical or efficient doing such thing on Calibre?

It all depends upon your specific use case.

I have a horror of putting any private content into the cloud. As such, the majority of document management solutions are, for me, unacceptable.