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Can two or more users share a database file over a local area network?


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Published by:
Troy Wolbrink
on 21 Oct 2008
6 people found this article useful.

85% of people found this useful
Can two or more users share a database file over a local area network?

It is relatively safe for multiple people to simultaneously edit the same TntMPD database over the network. Special care is needed to avoid data corruption. Let me unpack this:

TntMPD uses a file-based database system (MS Jet/Access to be precise). If TntMPD's connection to the database file is interrupted during a write operation, there's a really good chance for failure. Even the most reliable network will never be as reliable as a local hard drive. And as more users simultaneously connect to the file, the chance of a single point (the one file) failure goes up as well. Network failures, power failures, and Windows not flushing the write-behind cache if you don't shut down properly (or eject the USB drive properly) are all possible types of failure.

In practice, however, failures like this happen very rarely. But they do happen enough that I added an auto-backup feature to TntMPD so that every time you close the program a local backup is created (or a backup is created to the place you specify in the options).

So the best ways to avoid data loss:
1. Maintain a reliable file sharing server and network.
2. Maintain regular backups.
3. Encourage users with a shared database open over the network to close TntMPD when they are done using it.

I use the shared database feature every day when I sync to my wife's computer (using TntSync), and I've never had a failure since 1998 when I started using it. :)

--Troy

Recent Comments

By: Troy Wolbrink Posted on 6 Aug 2010 1:31 AM

I haven't heard of a way to get the Mac to open a database over a Windows (SMB) file server.  I've tried it, and TntMPD can see the file, but I get strange errors when opening the database.

I have heard of someone who got it working by hosting the file on a Mac and having their Windows computers connect to the Mac instead:  www.tntware.com/.../4284.aspx

By: Colby Weinhofer Posted on 19 Feb 2013 8:59 AM

Before reading this post, I was under the impression that a database could not be used by two people at the same time. A while back, I had even found and applied the "warn if someone else has the database open" option to prevent us from accidentally making this "mistake". However, it looks like I was wrong. If so, what is this option for?

Our database is currently stored on our home file server and my wife and I both access it over the LAN using an SMB share. Can you confirm if this is a safe / recommended way to do things. We have had a few scares where one or the other computer became disconnected from the network while TNTMPD was still open and we got all sorts of error messages (something about the MS jet engine, I think) and usually end up having to force quit the program. However, it has never caused an actual problem with our database.

By: Kate Hobbs Posted on 19 Apr 2013 6:19 PM

I am operating our database (which is held in dropbox) with my husband, both using separate computers.  I made changes to, and added, contacts.  I closed the database and exited.  Husband went into his record and was unable to see the changes I had made.  He tried closing the database, and then exiting, re-opening and still no amendments.  Waited over 12 hours and still no changes apparent.

I've changed my options to ensure that a back up is made each time the database is closed.

1. Why have the changes not taken effect?  To be honest, if this is not solved, then the database really isn't as useful to us as we had hoped.

2. I ticked the box that asked if I wanted to be made aware when the database was open on another computer, thereby receiving notification that my view was Read-Only.  To date, neither my husband or I have ever seen such a notification.  

Help please.

By: Troy Wolbrink Posted on 19 Apr 2013 11:23 PM

Hi Kate, it's still possible for both people to change the database at the same time, even with "Dropbox Mode" turned on in TntMPD.  That mode only works well when both people are connected to the internet all the time, and they don't both open the database within a minute of the other (so the "signal" file has a chance to propagate over Dropbox).

Some help is coming in TntMPD 3.0 to make sure no one's changes get lost.  You might noticed some "conflicted copy" files next to your database?  These are the "losing" databases when two people changed the database at the same time.  In TntMPD 3.0, it will offer to automatically import any more recent changes from these losing databases.  TntMPD 3.0 is coming soon!

By: Troy Wolbrink Posted on 19 Apr 2013 11:25 PM

Colby, sorry I took so long to notice your comment.  The "Dropbox Mode" option (where it warns if someone else has the database open) is there for Dropbox users.  Since they are not on a Local Area Network, they can't both be making changes at the same time. But on a LAN you can (but only if you're a Windows user on a Windows LAN).

By: Kate Hobbs Posted on 6 May 2013 2:53 AM

Troy - ir qould be very helpful to know when v.3.0 is coming as my hubby and I continue to have two copies of the d/base which will not configure.  It is now getting incredibly frustrating for me to make changes and not to see them reflected in my hubby's copy and vice versa.  The d/base is really not functioning in the way we need it to and is only creating a duplication of work as things stand.

By: Troy Wolbrink Posted on 10 May 2013 2:32 PM

Hi Kate,  TntMPD 3.0 is in testing right now (www.tntware.com/.../tntmpd-3-0-2-lots-of-bug-fixes-and-some-new-features.aspx)  I'm hoping to see it go beta in a few weeks.  --Troy

By: Roger Miller Posted on 13 Aug 2013 8:47 PM

we are entering our contacts on one computer  we closed that out and I tried to enter the tntmpd program on another computer my profile comes up but I am stuck on the  intro page and user guide. how do I get to contacts???

By: Troy Wolbrink Posted on 13 Aug 2013 9:23 PM

Click the "Contacts" button on the left side of the main screen.

By: Roger Miller Posted on 14 Aug 2013 2:15 AM

I click contacts and got  browse tabs I would like get into the contact list to add my contacts   thanks!

By: Troy Wolbrink Posted on 4 Sep 2013 11:44 PM

To add a new contact, click the "New Contact" button.  That's explained further here:  www.tntware.com/.../contacts_addedit.aspx

By: Jeremy Kupsch Posted on 25 Sep 2013 12:51 AM

I am brand new to TNT.  My wife and I are just starting out as missionaries.  We both have Mac computers.  If I download TNT on both our MacBooks can we share a database?  Can I put TNT on a external hard drive?  To transfer all our donor contacts will be a big job and I don't want everything on one computer and it crash on me.  Help please

By: Troy Wolbrink Posted on 26 Sep 2013 2:36 PM

I'd recommend using Dropbox to share your database between computers:  www.tntware.com/.../how-can-tntmpd-3-0-help-me-use-dropbox-better.aspx

By: RaymondRay Posted on 27 Jan 2015 7:45 PM

Troy,

I use a PC. How do you share a TNTMPD database with 2 people and save all the changes? What are the commands on TNTMPD? How is this done without using two databases on two PCs?

Raymond Ray  

By: Troy Wolbrink Posted on 30 Jan 2015 7:16 PM

Hi RaymondRay,  If you can setup a Windows LAN (local area network), you can create a file share and put your TntMPD database on it and give others read-write access to the folder it's in, then two people can open the database at the same time, and work simultaneously.

If the above makes no sense, stick to Dropbox!  :)

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