Strange Happenings with Several Databases. 3

[Ed2020]

Hi,

Over the past couple of weeks a number of different developers within the company I work for have been having problems with their Access databases. Users have been receiving three different error messages when opening the systems:

1. You do not have permissions to open this database exclusively.
2. You do not have permissions to open the backend database file.
3. Disk or network error.

The disk or network error also occurs after the users have successfully opened the system and been using it for a period of time.

All three messages are intermittent. Often retrying immediately after receiving the message everything works perfectly. Sometimes (particularly with the disk or network error) you have to wait several hours before the database can be opened.

When the disk or network error message is received it is not possible to do anything with the file in Windows Explorer either - it cannot be copied/moved to another directory or drive. Other files in the same directory can still be accessed/moved/copied/deleted. We've checked the permissions on the directory in which the databases are stored and the permissions on the database objects and everything is fine there.

This doesn't feel like an MS Access problem to me, however we're having difficulty convincing the people who look after our servers and networks that it isn't just a problem with the databases. My guess is another process is intermittently locking the files preventing Access from reading them and this is what's causing the different messages (disk/network error if the mdb file is locked, permissions errors on the backend if the mdw is locked, open exclusive permissions messages if the ldb is locked). I just can't prove it!

Has anyone seen anything like this before? If anyone can shed any light I'd appreciate it.

TIA,

Ed Metcalfe.

Please do not feed the trolls.....

 

[MakeItSo]

My guess is another process is intermittently locking the files

Sounds like the most logical conclusion to me.
My money would be on enterprise "Anti Virus".

[navy]"We had to turn off that service to comply with the CDA Bill."[/navy]
- The Bastard Operator From Hell

 

[smedvid]

My guess is that all these MDBs are on a network directory share...

Has something changed in the network topology? Sounds like network issues may be the key here... Get a sniffer to trace packets... etc...

A couple of years ago, the network engineers tried to optimize performance by tweaking packet size and installed a tool to monitor stuff... Well... We kept getting the "Disk or network error"; especially on the larger MDB files we worked with; most of which exceeded 1GB is size (after compacting)...

Once changes were backed out of network... everything was ok! Took 3 weeks to convince IT Team that issues was reproducable. They kept saying it was a coding issue in MS Access MDBs...

Good luck...
htwh,


Steve Medvid
IT Consultant & Web Master

http://www.saveourfarm.com

Chester County, PA Residents
Please Show Your Support...

 

[Ed2020]

Thanks both. You've confirmed the two things at the top of my list of suspects.

I've done some initial checks on network connectivity and there's nothing immediately obviously wrong (although I haven't ruled it out altogether) so AV is my current theory. We're using eTrust AV which, IMHO, is second only to Norton in its crappyness. It's already caused other problems, so I'll not be at all surprised if this is the culprit. Proving it could be a challenge though.. :-(

If anyone else has any experience of problems like this I'd appreciate your input.

Ed Metcalfe.

Please do not feed the trolls.....

 

[Ed2020]

Addendum - The Wintel team swear nothing has changed in the last few weeks. Network engineers are saying the same.

Somebody is not telling me the truth...

Please do not feed the trolls.....

 

[smedvid]

If you can reproduce the issue consistently; then they can trace the traffic and it may lead to where the issue is based. I've seen bad network cables cause strange issues before as well as bad routers.... If the databases work on a local PC, then is should work the same on the network... See if you have another seperate network drive available; perhaps on a different server and sub-net... may help id where issue is located...
Good luck...



Steve Medvid
IT Consultant & Web Master

http://www.saveourfarm.com

Chester County, PA Residents
Please Show Your Support...

 

[jsteph]

You can go into the Computer Management MMC (Control Panel-->Administrative Tools-->Computer Management) and find "Shared Folders" and under that "Open Files". This would be from the server or machine where these .mdb's sit.

From there you can see "Accessed By" and other info, and you can delete the file-lock there. I've had to resort to this when the .ldb gets 'locked' by some phantom user which prevents others from accessing in certain contexts.
--Jim

 

[Ed2020]

smedvid,

Unfortunately I haven't managed to work out under what circumstances the problem occurs yet, so I can't reproduce the problem reliably. The most common issue happens more than 50% of the time, but is so brief (a retry almost always works) there isn't much window of opportunity for investigation. Frustrating!

jsteph,

Thanks for the suggestion. I'll look into that.

Ed Metcalfe.

Please do not feed the trolls.....

 

[MakeItSo]

We're using eTrust AV

Ha!
In that case you might want to rub this KBAlertz article into your IT guys' noses:

You may experience various problems when...

I may quote a certain passage:

When you try to open a Microsoft Access 2.0 database file (.mdb) in Microsoft Access 97, Access 2000, or Access 2002, you may receive an error message that resembles the following:
Disk or network error.
...
...
CAUSE
These problems may occur when one of the following conditions is true:

* The version of Symantec Event Handler driver (Symevent.sys) is outdated. Therefore, two or more threads are deadlocked in the Symevent.sys driver in the Symevent_GetSubTask function.
* There is a Computer Associates (CA) INO_FLTR.SYS OpLock interoperability problem with the Srv.sys file.


RESOLUTION
To resolve these problems, update the third-party antivirus file system filter driver. For example, if you have the Symantec Event Handler driver (SymEvent.sys) installed on the computer, update to version 11.6.4.1 or a later version. To obtain an updated version of the Symevent.sys file or to find help with the reconfiguration, visit the following Symantec Web site:

http://www.symantec.com

(

http://www.symantec.com)

;-)

I guess it's the AV after all...


[navy]"We had to turn off that service to comply with the CDA Bill."[/navy]
- The Bastard Operator From Hell

 

[Ed2020]

MakeItSo,

If I could give you another star I would do. Excellent find! My only slight hesitation is the age of the article - surely they're not using software that's that out of date!

Having said that it certainly agrees with the evidence we've seen so far. The only time we have reliably managed to reproduce the error message is first thing in the morning, so I'd got as far as surmising it's an overnight job which is locking the files. AV was going to be my first thing to investigate, followed by backups and Volume Shadow Copy. Hopefully you've saved me quite a bit of work!

Thanks again,

Ed Metcalfe.

Please do not feed the trolls.....