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VFP Error 1104 on Virtual Windows Server 2008 Terminal Server

We are running a VFP 9.0 SP2 application on a virtual terminal server (VMware running Windows 2008 Standard R2 64 bit) with Xbase data stored on second virtual server (VMware Windows 2008 SBS SP2 64 bit).  The data stored on that server is accessed by local workstations throughout the day without any issues.  Terminal server users logon at night and encounter intermittent VFP 1104 errors (error reading file) on different tables in random areas within the application.  Here are a few basic facts:

  The application works fine in other TS environments.
  There are never more than 8 concurrent TS users logged on at night.
  Neither server ever gets close to maximizing any system resources.
  Users do not complain about lags prior to errors.
  The antivirus software is configured to skip cdx, dbf, and fpt files.
  No backup or scheduled tasks are running during the errors.
  TS users can sometimes go several nights without any errors.
  The errors can occur anywhere within the application.
  Errors can sometimes be light (1-12 per night) or heavy (100+).
  On a night with heavy errors the users can sometimes work for an hour without any errors.
  Disconnected sessions close automatically after 15 minutes.
  All TS users have the same rights.
  All data folders and subdirectories grant full access to everyone.
  The TS is rebooted weekly.
  Rebooting the TS does not make errors any less likely.
  There are no system events to suggest

This is the additional error information passed back by the VFP AERROR() function:
  Error Number: 1104
  Error Text: Error reading file s:\netdata\tables\user.dbf.
  Error Table: s:\netdata\tables\user.dbf
  OS Error: 64
  OS Text: The specified network name is no longer available.

It is not as frequent, but sometimes the last two lines of AERROR() return:
  OS Error: 59
  OS Text: An unexpected network error occurred.

Thanks in advance for your time.
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1 Solution
Error 1104 simply means "Network was disconnected" and it is visible from your description already. Visual FoxPro cannot recover from this error obviously and the application crashes and data may be lost in such case.

Thw question should rather ask about network monitoring software because Visual FoxPro tools cannot provide any more information to resolve this odd behavior. I would guess it is caused by some incompatible VMware driver or by its setting at least.

You may create a simple VFP application which will access data on the server from VMWare client and run it together with network monitoring software. It should tell what is hapenning.

Sorry, I cannot help more.
ttdaleAuthor Commented:

I have not been able to reproduce the issue.  I can login the TS with a duplicate profile of one of the remote users and run the application anytime day or night without any errors.  I have even been in the application during a time when they were encountering the errors.  Again, everything worked fine for me.  This one is literally keeping me up at night.
The issue of VFP application's sensitivity to network problems has been discussed a number of times in this forum.

One way to address these problems is to modify your VFP code to be more 'fault tolerant' with TRY/CATCH   and/or  ON ERROR processing methods

Another suggestion that we offered was to write a small stand-alone test application to run 24/7 which would attempt to write a small file to the server and then read it back.   In the event of a problem, you would capture the Date & Time and any other pertinent info.

If, while running that test app, you found that the problem appeared, you could then analyze if this was occurring at a persistent time of day or any other common parameters.

If you should happen to have found that it was occurring at a particular time of day, then you might work with your network administrator to determine if events like Backups were occurring or other events like extensive file transfers which could 'flood' the network.

Good Luck
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Just one off-topic note:

My ADSL connection was falling down after the sun set everyday... We have been switching to different wire pairs, exchanging the house wall outlets etc. Nothing helped and technicians do not work over night...

So, I am on 5 GHz WiFi now and its stability is much better.

Maybe the best you can do is to change VMware for something else...
ttdaleAuthor Commented:

Yes, 1104 have been discussed a number of times in this forum.  I read every post.  However, almost every instance has been with Windows Server 2000/2003.  This is happening on two virtual machines (VMware) running Windows Server 2008.  Those two machines are located in the same server farm – networking/connectivity issues should not be an issue.  As for making the application more fault tolerant, I suspect that it would only cause it to hang for extended periods of time.

The application logs every error.  I have sent that information to the IT group that maintains the servers and they claim that there is nothing happening behind the scenes during those times.  There is nothing in the event logs to hint at any possible conflicts.  There is no point where the system resources drop to questionable levels.  As far as the IT group is concerned, their systems are operating properly.

" their systems are operating properly."

Hmm, "OS Error: 64,  OS Text: The specified network name is no longer available" is nothhing for them,
100+ errors over night... They are very tolerant. It should crash in other applications, as well.

If you'll ask some C programmer to write simple monitoring routine which will simulate DBF file reading, locking and writting then it should show the truth.

BTW, Windows 2008 is supported, Visual FoxPro extended support period is still in progress, you may ask Microsoft for help. If they say VFP has paid support only then you may show similar error in MS Access or in C. I don't know how deeply they like VMware but you may try it.
ttdaleAuthor Commented:

I knew that I could log a call with Microsoft, but I wanted to try here first.  When I logged a call with MS, they offered several suggestions to limit foreground and background memory – which I promptly implemented.  However, none of those changes altered the frequency or the duration of the errors.  The call is still open, but I am trying to escalate it outside of the VFP group.

The hardware vendor, in an effort to eliminate the possibility of the issue being related to the antivirus software, completely uninstalled Kaspersy from the TS.  That also failed to alter the errors.  Now they are wondering if this issue is related to SMB 2.0.  They are pursuing that from their end.

I also found several references to opportunistic locking (http://support.microsoft.com/kb/296264).  It would seem strange for that to be the root of this issue (since they can operate several days without any errors), but I will take a strange fix over a lost client any day.
If SMB2 and oplocks are not the cause then possible source of this error could also be the hardware. Some hardware errors are not traceable sometimes. Errors may cause data damage or break the network connection. The mallfunction can appear occassionaly or during the higher level of traffic etc. and the only fix is to replace mallfunctioning part(s) which are hard to identify.

I remember one SCSI card swapping some bits of information stored on a harddrive during the high load... These bits were swapped even during the reading data from DBF files... So, everything can happen.

The obvious procedure is to use the whole new machine for tests and then to start with particular parts replacements...

I can just wish you a good luck now..
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