Concurrent access to Calibre Library

WaldoPepper · 01-14-2015, 02:50 AM

Hello,

maybe this has been answered in the past, but I could not find an older thread regarding this topic.

My Calibre library (folder) resides on a NAS, where I can access it form any PC and laptop in my home network.

I have a headless Linux server running on which Calibre is running as content server in "daemonized" mode, accessing the library on the NAS, too.

I read my books on several tablets using the "CC Companion" to access the Calibre content via the linux server.

From time to time I start Calibre on one of my laptops or PC's to import a book, fine tune some metadata or do some maintenance. I use the Calibre library on the NAS sort of concurrent then. Is this an intended way to do with Calibre?

Up till now it works fine. Only from time to time a newly imported book does not show up, in this case I just restart the Calibre "daemon" on the linux machine, which does fix this.

Can anybody comment if I am doing it in the right way?

Thanks in advance.....

Kai

darryl · 01-14-2015, 02:58 AM

This is mentioned in a number of threads. It is a very good way to corrupt your data. Currently Calibre is intended for single access only and use on an NAS is not recommended. I also have my Calibre Database on an NAS and it works well. However, I am careful to limit access to single access and keep a recent backup of the whole library on another machine. I have had to rebuild the database once after accidental concurrent access.

I recall at one stage Kovid, the developer of Calibre, was working on a different database backend but I'm not sure if there are currently any plans to support concurrent access. At the moment concurrent access is just asking for corruption problems.

WaldoPepper · 01-14-2015, 03:30 AM

Thank you for your quick reply and the information you provided.

One additional bit of information: I am running the content server "calibre-server" on my linux box. Dont know if this makes any difference....

It dawned on me that the way I do it was not intended, though I do this for almost a year now and imported over 500 books up until now without a mayor incident. But maybe I am living on borrowed time here... ;-)

Is there by any means an alternative? Maybe there is a client with book-import and metadata editing capabilities which I can use to maintain a "daemonized" Calibre?

mbovenka · 01-14-2015, 04:48 AM

Quote:

Originally Posted by WaldoPepper

Is there by any means an alternative? Maybe there is a client with book-import and metadata editing capabilities which I can use to maintain a "daemonized" Calibre?

Don't run your Linux Calibre daemonized and use X or VNC or what-have-you to connect to it to do the maintenance and import (you could create an import directory on the NAS and have Calibre do the importing automatically)

As far as having your library on a NAS...for some it works, for others it doesn't. It's not supported (and actively discouraged) by Kovid, so yer pays yer money and yer takes yer chances. It worked for me, until I got cold feet and moved to a local disk with a copy on the NAS I keep up to date with FreeFileSync.

darryl · 01-14-2015, 05:09 AM

The main point is that you should only have the database itself connected to one instance of Calibre. If the connected instance is running the Content Server (I'm not sure aboutthe Wireless Connection), it is quite okay for multiple client's to connect to these. What you should not be doing is running more than one instance of Calibre itself accessing the database. So if you want to run Calibre itself on one of your desktops or notebooks to import books, edit metadata etc, you should shut down the instance on your headless server first to avoid possible problems. Always remember what you are doing is dangerous and you may run out of luck. So always keep good backups.

itimpi · 01-14-2015, 05:23 AM

You are OK as long as you are only ever running a single instance of Calibre main program against the database. The content-server has read-only access. As long as the content-server is running on the same machine as the main calibre program then calibre should automatically restart it when books are added. If you run the content-server on a different machine then the responsibility of restarting the server to see new books is now up to you.

PeterT · 01-14-2015, 08:06 AM

See if this thread has any applicable ideas. How to set up a content server on a VPS?

Take a look at the scripts used by chaley to automate his enviroment

theducks · 01-14-2015, 11:15 AM

Quote:

Originally Posted by darryl

T (I'm not sure about the Wireless Connection)

The Wireless connection is a Single Device, Not a user connection.
(USB)Wired, Wireless or Connect to Folder.

In all cases, these are Device PUSH connections (you see the 'On Device' column)

darryl · 01-14-2015, 11:19 AM

Quote:

Originally Posted by theducks

The Wireless connection is a Single Device, Not a user connection.
(USB)Wired, Wireless or Connect to Folder.

In all cases, these are Device PUSH connections (you see the 'On Device' column)

Obvious when you think about it. Thank you.

WaldoPepper · 01-15-2015, 02:00 AM

Thank you all for your input and the pointers to the additional information. Now I have a more profound understanding about how to tweak my environment.

This forum is a great resource and Calibre is such a great tool and is the prime "enabler" for my transition from printed to scanned/electronic books....

01-14-2015, 02:50 AM	#1
WaldoPepper Junior Member Posts: 5 Karma: 10 Join Date: Jan 2010 Device: Xoom, Galaxy Tab 4, iPad 2, Nexus 7, Fire HD, SurfTab Wintron 10.1	Concurrent access to Calibre Library Hello, maybe this has been answered in the past, but I could not find an older thread regarding this topic. My Calibre library (folder) resides on a NAS, where I can access it form any PC and laptop in my home network. I have a headless Linux server running on which Calibre is running as content server in "daemonized" mode, accessing the library on the NAS, too. I read my books on several tablets using the "CC Companion" to access the Calibre content via the linux server. From time to time I start Calibre on one of my laptops or PC's to import a book, fine tune some metadata or do some maintenance. I use the Calibre library on the NAS sort of concurrent then. Is this an intended way to do with Calibre? Up till now it works fine. Only from time to time a newly imported book does not show up, in this case I just restart the Calibre "daemon" on the linux machine, which does fix this. Can anybody comment if I am doing it in the right way? Thanks in advance..... Kai

01-14-2015, 03:30 AM	#3
WaldoPepper Junior Member Posts: 5 Karma: 10 Join Date: Jan 2010 Device: Xoom, Galaxy Tab 4, iPad 2, Nexus 7, Fire HD, SurfTab Wintron 10.1	Thank you for your quick reply and the information you provided. One additional bit of information: I am running the content server "calibre-server" on my linux box. Dont know if this makes any difference.... It dawned on me that the way I do it was not intended, though I do this for almost a year now and imported over 500 books up until now without a mayor incident. But maybe I am living on borrowed time here... ;-) Is there by any means an alternative? Maybe there is a client with book-import and metadata editing capabilities which I can use to maintain a "daemonized" Calibre? Last edited by WaldoPepper; 01-14-2015 at 03:35 AM.

01-14-2015, 05:09 AM	#5
darryl Wizard Posts: 3,108 Karma: 60231510 Join Date: Nov 2011 Location: Australia Device: Kobo Aura H2O, Kindle Oasis, Huwei Ascend Mate 7	The main point is that you should only have the database itself connected to one instance of Calibre. If the connected instance is running the Content Server (I'm not sure aboutthe Wireless Connection), it is quite okay for multiple client's to connect to these. What you should not be doing is running more than one instance of Calibre itself accessing the database. So if you want to run Calibre itself on one of your desktops or notebooks to import books, edit metadata etc, you should shut down the instance on your headless server first to avoid possible problems. Always remember what you are doing is dangerous and you may run out of luck. So always keep good backups. Last edited by darryl; 01-14-2015 at 05:11 AM.

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01-14-2015, 02:58 AM	#2
darryl Wizard Posts: 3,108 Karma: 60231510 Join Date: Nov 2011 Location: Australia Device: Kobo Aura H2O, Kindle Oasis, Huwei Ascend Mate 7	This is mentioned in a number of threads. It is a very good way to corrupt your data. Currently Calibre is intended for single access only and use on an NAS is not recommended. I also have my Calibre Database on an NAS and it works well. However, I am careful to limit access to single access and keep a recent backup of the whole library on another machine. I have had to rebuild the database once after accidental concurrent access. I recall at one stage Kovid, the developer of Calibre, was working on a different database backend but I'm not sure if there are currently any plans to support concurrent access. At the moment concurrent access is just asking for corruption problems.

01-14-2015, 05:23 AM	#6
itimpi Wizard Posts: 4,553 Karma: 950151 Join Date: Nov 2008 Device: Sony PRS-950, iphone/ipad (Marvin/iBooks/QuickReader)	You are OK as long as you are only ever running a single instance of Calibre main program against the database. The content-server has read-only access. As long as the content-server is running on the same machine as the main calibre program then calibre should automatically restart it when books are added. If you run the content-server on a different machine then the responsibility of restarting the server to see new books is now up to you.

01-14-2015, 08:06 AM	#7
PeterT Grand Sorcerer Posts: 13,511 Karma: 78910202 Join Date: Nov 2007 Location: Toronto Device: Libra H2O, Libra Colour	See if this thread has any applicable ideas. How to set up a content server on a VPS? Take a look at the scripts used by chaley to automate his enviroment

01-15-2015, 02:00 AM	#10
WaldoPepper Junior Member Posts: 5 Karma: 10 Join Date: Jan 2010 Device: Xoom, Galaxy Tab 4, iPad 2, Nexus 7, Fire HD, SurfTab Wintron 10.1	Thank you all for your input and the pointers to the additional information. Now I have a more profound understanding about how to tweak my environment. This forum is a great resource and Calibre is such a great tool and is the prime "enabler" for my transition from printed to scanned/electronic books....