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Multiple-user Access file issue with switching to Synology NAS server from Windows 2003 Server

Posted on 2014-11-19
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Last Modified: 2014-12-25
Hey,

I am not familiar with Microsoft Access, however we have a customer who upgraded from Windows Server 2003. All his business files were stored on that server and are now copied to the new NAS server. One of these files is a Access file (rolodex.mdb) which we are having issues with.  Multiple users are mapped to this NAS server and 4 of these users need simultaneous to the Access file.  Simultaneous access to this file was no problem under Windows. Now under the NAS device only one user can open the file by clicking on the shortcut/file which opens fine. If that file is open on the network and another user tries to open it nothing opens (no error messages, no event log files, nothing) it just acts like your clicking in empty space.  A workaround (which the customer says is unacceptable) is to open Access on subsequent computers that need to open the file and open the rolodex.mdb file from within Access.

 Most everything on the network is working fine at this point.

My questions is can we fix this so all 4 users can access this Access file by just executing the shortcut AND are there any other potential problems in accessing this file from the Linux NAS server (would Windows be better)? They don't want to go back to Windows server so we really need to make this work safely if possible.

Thanks!
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Question by:ImImIn
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Jim Dettman (Microsoft MVP/ EE MVE) earned 500 total points
ID: 40452897
<<Now under the NAS device only one user can open the file by clicking on the shortcut/file which opens fine. If that file is open on the network and another user tries to open it nothing opens (no error messages, no event log files, nothing) it just acts like your clicking in empty space. >>

 I've seen exactly this only once before, and under a Windows network to boot, so it's not the NAS per say.  I've never gotten to the bottom of it however as the client decided to live with the problem (it was a seldom used database).

<<
My questions is can we fix this so all 4 users can access this Access file by just executing the shortcut AND are there any other potential problems in accessing this file from the Linux NAS server (would Windows be better)? >>

 With that said however, Access is not supported on anything other than a Windows OS and did have problems with NAS's in general early on.

 For multi-user Access, the DB engine associated with Access, which is JET/ACE, uses extended byte range locking.  By that I mean it takes out locks through the OS on parts of the file that don't exist.

 What JET does when it connects to a DB file is:

1. Create a .LDB file in the same directory as the DB if one does not exist.
2. Enters the workstation name and Access user name (always 'Admin' if your not using Access security) in a slot in the .LDB file.

  The LDB file is an array of 255 slots of 64 bytes each, 32 for the machine name and 32 for the user name.

3. It grabs the first page of the database and initializes some status variables that pertain to the user slot.

4. It takes out a user lock on the LDB file (all locks are placed against the LDB file) for the slot number.  This lock is used to tell who has an active connection to the DB.

 Locks are taken out on the .LDB file with the OS that hosts the file.  However all the processing is done client side where MSACCESS.EXE is running.   The OS hosting the DB file itself only acts as a file share.

 Something is interfering with that process along the way and I'm not sure why a double click yields nothing.  It just doesn't work for some reason.   I should also add that when JET can't open a file in multi-user mode (say it can't create the .LDB file), then the file is opened exclusive.

 As I said, I have this happening at one client now and this happened when they moved to a VMWare setup with Windows 2008 Server R2, which is running Terminal Services.   Prior to that, they were running Windows 2003 on physical servers and did not have the issues.

I believe it's related to security and somehow involves the registry, but I am not positive.

So first thing to check is the basics:

1. Make sure the DB is not being virus scanned at open.
2. Make sure all users have full read, write, and delete privs for the directory where the DB resides.
3. With all users out, delete the .LDB file if one exists.
4. Reboot the NAS

 now test and see if you still have the same problem.

Jim.
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by:Gustav Brock
ID: 40452900
Sounds like a missing rights issue. Users must have read/write/create/delete rights on the folder to control the locking ldb file.

/gustav
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ID: 40452903
The other thing I should add is that JET can generate a considerable number of locks.   Not sure what your NAS allows, but it should allow 10,000 per user as this is the JET default.

If a large DB however, you often will see 100,000 locks or more attempted.  

Jim.
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by:PatHartman
ID: 40452995
I'm not sure if this will shed any light on the issue but for about three weeks in late October and early November, I was not able to open Excel files by double clicking.  I'm using O365 on Win 7 and I'm sure the issue was caused by some random patch that was ultimately fixed.  The problem only affected Excel.  It did not affect Access.  The problem disappeared some time last week.
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