.dwl (locking files)

[mom of 3]

Yesterday, my "wonderful" boss was asking what a .dwl file was. The last I knew, it was a temp file which was created in the project directory, if someone had that .DWG file open, right?????? Then, when the .DWG is closed, it automatically disappears, right? Well, being the person that he is, he said that the .dwl was still there. I didn't think that would be the case, or is it? I have not seen any .dwl files in any of my current projects, so I thought I'd ask. Am I way out in left field again?
(2004 with LDD)

[Eddie]

It's basically a LOCK file for the drawing

[architech]

this was posted by Hendie somewhere else....

Have you had drawings you were working on change to “Read Only” for no apparent reason ? AutoCAD goes and tells you that the file is being accessed by another session when you know for a fact that you are the only person working on that particular drawing. The only way out is to do a “Save As”, exit, delete the original, rename the copy and start up again.
I had this problem last year and it caused me nightmares. I have now seen the question pop up on a few forums recently and thought this may be of interest to you all. (Thanks go to Jason Martin for the great explanation)
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Read-only problems: Read-only's are generally related to timing issues between the server and the client.
The basics of the AutoCAD save procedure is:
1. AutoCAD verifies the file lock that it created previously (either at file open or on last save)
2. AutoCAD creates a new temporary file, and locks it. The current drawing information is written to the temporary drawing.
3. AutoCAD deletes the .bak file.
4. AutoCAD sends a remove lock request for the original .dwg.
5. AutoCAD tries to rename the .dwg to a .bak. General problem location: Usually when a read only occurs the server has not completed the remove lock request. The rename is then treated as a sharing violation and the rename request is denied by the server.
6. AutoCAD unlocks the temporary drawing.
7. AutoCAD renames the temporary drawing to the original drawing name. The read only problem can occur here as well, as if the file lock is not removed before the rename request is made, there is a sharing violation and the rename request is denied.
8. AutoCAD then re-locks the original drawing name.
Things that can cause these problems are as follows:
Very fast workstations and a "slow" server.
Network saturation
Excess server workload
Virus protection on the client
Virus protection on the server
"Misbehaving" network drivers on the client or on the server.
Bruce McCallum indicates updating his video drivers solved a problem that he was having with this, which doesn't make much sense, but as dependant as AutoCAD is on the video interface, is a possible candidate.
This problem isn't necessarily an Autodesk problem , but a network timing issue. The fix for
this problem is illusive and sometimes expensive (new servers, additional servers, faster networks, more isolated (switched) networks, etc). Autodesk people that I have spoken to have indicated that every time that they've seen this (actually seen it, at a customer site) the solution was to increase client to server throughput. Without fail, that's been the solution. The problem is more evident with AutoCAD, because of the complicated write. There are more chances for things to fail with so many file locks, un-locks, and renames. Autodesk's file write method is completely compliant with Microsoft's API requirements, but when the server doesn't respond within the designated period, the write fails (actually the rename fails) and the user is left with a temp file.