MobileRead Forums - View Single Post

ShellShock · 02-14-2026, 07:42 AM

I think there are two fundamentally different access scenarios here:

Calibre library on network storage/cloud storage/NAS

The Calibre library is stored entirely remotely and there is no local copy, so file I/O from the local Calibre process is over the network/internet. This is what the SQLite web site is warning against. I don't have any experience of this but I am sure their warnings are valid.

Calibre library on local storage

The Calibre library is stored entirely on the local file system, and all file I/O from the local Calibre process is to the local file system, as normal. In addition, there is a separate file syncing process (e.g., Dropbox) that synchronises the library files with a remote copy e.g., in the cloud.

This is the scenario I use and am familiar with. Here the situation is more nuanced. I use it to partly backup my library, but mainly to enable me to download epubs in the library (synced to the Dropbox cloud) to my IPad for reading, using an IOS Dropbox client.

We can assume that Calibre needs full access to the files in its library, for reads and writes, and will use shared as well as exclusive locks (e.g., for writes).

Ideally, we want the syncing process to only use shared reads on the library so as not to interfere with Calibre. I take the risk that, as long as I only change library files using Calibre, then Dropbox will detect these changes and use a shared read to copy the changed files to the Dropbox cloud.

As I am only interested in accessing the epubs in the library from other devices, I have recently excluded the Calibre database (metadata.db) and other related files from Dropbox synchronisation. How to ignore files in Dropbox is explained here https://help.dropbox.com/sync/ignored-files. Of course, this requires an alternative backup mechanism for these excluded files, as it is no longer using Dropbox as a backup.

It is also possible to pause Dropbox synchronisation whilst using Calibre, to be double-sure.

I consider the trade-off of potential file corruption versus the convenience of remote access to my ebooks is worth it, but others should decide this for themselves.

02-14-2026, 07:42 AM	#6
ShellShock Wizard Posts: 1,181 Karma: 2431850 Join Date: Sep 2008 Device: IPad Mini 2 Retina	I think there are two fundamentally different access scenarios here: Calibre library on network storage/cloud storage/NAS The Calibre library is stored entirely remotely and there is no local copy, so file I/O from the local Calibre process is over the network/internet. This is what the SQLite web site is warning against. I don't have any experience of this but I am sure their warnings are valid. Calibre library on local storage The Calibre library is stored entirely on the local file system, and all file I/O from the local Calibre process is to the local file system, as normal. In addition, there is a separate file syncing process (e.g., Dropbox) that synchronises the library files with a remote copy e.g., in the cloud. This is the scenario I use and am familiar with. Here the situation is more nuanced. I use it to partly backup my library, but mainly to enable me to download epubs in the library (synced to the Dropbox cloud) to my IPad for reading, using an IOS Dropbox client. We can assume that Calibre needs full access to the files in its library, for reads and writes, and will use shared as well as exclusive locks (e.g., for writes). Ideally, we want the syncing process to only use shared reads on the library so as not to interfere with Calibre. I take the risk that, as long as I only change library files using Calibre, then Dropbox will detect these changes and use a shared read to copy the changed files to the Dropbox cloud. As I am only interested in accessing the epubs in the library from other devices, I have recently excluded the Calibre database (metadata.db) and other related files from Dropbox synchronisation. How to ignore files in Dropbox is explained here https://help.dropbox.com/sync/ignored-files. Of course, this requires an alternative backup mechanism for these excluded files, as it is no longer using Dropbox as a backup. It is also possible to pause Dropbox synchronisation whilst using Calibre, to be double-sure. I consider the trade-off of potential file corruption versus the convenience of remote access to my ebooks is worth it, but others should decide this for themselves.