Stall/hang on copy to network drive

[aussieboykie]

I regularly compare a local folder structure on my company supplied laptop with a backup structure on my desktop accessed via a network share - e.g. Net Use X: \\DeskTopPC\C$ then compare C:\MyStuff with X:\MyStuff. Most of the time the subsequent copies of new/changed files in selected folders proceed without any problem but about one in ten times a copy operation hangs. Whenever this happens, the hang is unrecoverable and whilst I can continue to use other applications on the laptop, I can't shut it down gracefully even if I "force" BC3 to be killed during the Windows 7 shutdown. It does not matter how long I wait, the system never shuts down until I hit the OFF switch.

I can't determine any pattern and it is not Windows 7 specific. The same thing used to happen on XP on a previous (corporate) laptop. Sadly, it's not reliably repeatable. Typically the same copy, when restarted after a hard stop and restart, completes without a hiccup. If it's any help, the pattern seems to be...

1. Compare then select a folder, or folders, with new/changed files.
2. Click the button to copy to other side.
3. Files start to copy but operation stalls on file XYZ, apparently part way through.

On checking the desktop, the stalled XYZ file copy is invariably complete which suggests that the stall is not really a stall at all. The real annoyance, of course, is the need to do a hard restart. I didn't think applications were able to cause that to happen under Windows 7. (BTW, using Process Explorer to kill BC3 doesn't help. Still needs a hard restart.)

Regards, AB

[kevinsikes]

Try disabling SMB2 and SMB3 protocols in Win7 by creating DWORD values named SMB2 and SMB3, each with a value of 0, under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\LanmanServer\Parameters . Reboot and try your copy again. I used to get hard lockups with my Win7 - XP client shares, and disabling SMB2 fixed the issue for me (I was on Vista at the time, so only SMB2 needed to be disabled).

**NOTE** there may be a stray space in the registry key above. I have tried a few edits to fix it, but it won't go away. Grrrr.

[aussieboykie]

Thanks Kevin, that looks very promising. I will apply this change on both systems since I copy both ways. Hopefully there are no unfortunate side effects from disabling SMB2/3.

My guess has always been that BC3 hangs waiting for a response that never arrives. This post seems aligned with that view. If I'm right, then perhaps the problem can be fixed (or at least bypassed) by means of a timeout.

Regards, AB

[Zoë]

Hi AB,

It's unlikely that we'd be able to add a timeout here. None of Windows' filesystem functions take timeouts, so the only way to do it would be to forcibly kill the thread involved, and that could seriously destabilize BC when it happens. I'd like to look into separating out multiple processes, like web browsers are doing for tabs now, and we could just kill the process then, but that's a long term project, and won't occur soon.

[aussieboykie]

Sadly, switching off SMB2 and SMB3 has not done the trick. I've just performed another hard reboot. Looks like I'll have to forego syncing across network shares with BC3. My alternative is to use Directory Opus synchronise. To date, I have never had this problem using DO but to be fair, I haven't used it as much for this purpose.

Regards, AB

[lhasadad]

I have seen hangs but think this is more a Win7 or Win2008r2 Network Stack issue. there is a KB article at MS that indicated there may be a stall that can occur when deadlock hits in the stack. my guess is BC is more susceptible to it because of the way it drives the API's.

[lhasadad]

More info

I have noticed it primarily happens when running lan connected (vs over more distant connection (Like a vpn over cable modem). it appears to generate a hard lock on the copy operation (the gui is still responsive but can't terminate the copy nor can I exit beyond compare. Using something like ProcessExplorer i can find and kill BC which kills off the gui. but I still see
something in the process list that appears to be the last remnants of BC hanging around waiting on something.

[lhasadad]

win 7 copy from hangs

Seems this is mainly an issue with copying things from the win7 system to the 2008r2 system. other direction seems to run fine.

I have noticed it primarily happens when running lan connected (vs over more distant connection (Like a vpn over cable modem). it appears to generate a hard lock on the copy operation (the gui is still responsive but can't terminate the copy nor can I exit beyond compare. Using something like ProcessExplorer i can find and kill BC which kills off the gui. but I still see
something in the process list that appears to be the last remnants of BC hanging around waiting on something.

[Aaron]

How long do you wait before manually killing the BC3 process? The timeout may take awhile to return. If you give it a long time (5-15 minutes), does it ever return?

[lhasadad]

I have seen it never return and I have seen copies complete after a long (minute or more (did not time it) pause).

[lhasadad]

BTW, I think it fails most often and most consistently on LAN connection on same gigabit switch. (That is, a very low latency, very high speed connection).

[Aaron]

How long did you give it for a "never return" scenario? Longer than 15-30 minutes, I assume?

I would expect less than 5, but as a troubleshooting step, it's good to be extra certain and give it the extra time to try and complete. Normally 1-2 minutes is all that would be needed.

[gaverj]

I have the same issues. I am transferring video files to my storage server on the same LAN. Doesn't seem to matter if it is a copy, move or even a delete function. It randomly locks up and the only way to recover is a hard boot. I can choose several file to copy or move over and it gets say 91 mb into the first file and stops. I have left it overnight and still hangs. I can end proccess and it closes the gui but it still shows BCompare.exe in the task manager. The only way i can kill it is to force shut off the machine. a shut down will not work, have left that oin overnight to still waiting to shut down in the morning. Have had this issue for a while and am now trying to find a solution as when this hangs it also cause issues in other programs.

[gaverj]

I have the same issue, I am trying a work around of running my remote file server as an FTP instead of using windows drive mapping

[Zoë]

Hi gaverj,

That certainly sounds like an issue with the network stack, below BC. Make sure that your network drivers are up to date and that you don't have any pending OS updates on either computer.

I don't usually like recommending FTP over a drive mapping, it it shouldn't have the same hang issues that drive mappings can potentially have. Those calls can have timeouts and we will forcibly close the connection if you try to close the window.