TCPIP$FTP_CLIENT hangs

[Matthias Djurkovic]

Hi Antonio,

I can understand that you are confused ;-)

Problem is: there is a job that is running approximately 15 hrs a day and checking for new files to transfer (all files between 3 - 60 Blocks in size) every 5 minutes. These files have to be on the Windows machines at least nearly "in time".

If we now have a stalling transfer and don't realise, the job will stall forever (because of 1 single file) and the remaining files will not reach their target. This is obviously a problem.

Now, if we get the feedback from FTP_CLIENT that it doesn't work, the stalling/hanging is away and the job will retry the next time. And this is exactly what happened last night:

we got the message, and the transfer aborted. 5 minutes later, the job found the same file again and sent it to the target (because 5 minutes later the FTP worked again).

So, yes: it "worked"! At least it reported back the error instead of hanging around for ages!

I know, that this is not the "real" solution to the problem but at least the files will reach their target and we can concentrate on solving the "real" issue (like network problems and such).

So long, and thanks very much for your efforts!

Matthias

[Wim Van den Wyngaert]

Matthias,

If I (and Antonio ?) understand correctly, windows NT is not reacting as it should with the result that a transfer goes into hang. You solved the hang by setting keepalive. The real problem is on NT and is not solved. Correct ?

Wim

[Matthias Djurkovic]

Hi Wim,

you are probably correct.

However, I believe it to be incorrect behaviour for TCPIP$FTP_CLIENT to stall forever (and this is really forever) if there is something wrong with the connection while waiting to receive data!

So it is probably on the Windows side but could be on the network side as well. In fact, I believe it to be something with the network, because of the sudden increase of incidents. We usually had this problem maybe once or twice a month and only yesterday it started to become a real and urgent problem.

So we had to find a solution/work-around on the VMS-side. I think it's the same in most companies: Windows-Side is always correct and OpenVMS-side isn't...

So long,
Matthias

[Antoniov.]

Matthias,
if you are patient and you have got time you can execute TCP/IP troubleshooting techniques decribed here
http://h71000.www7.hp.com/doc/732final/6631/6631pro_contents.html#toc_chapter_1

Good Luck
Antonio Vigliotti
P.S.
Obviuosly you can post again :-)

[Wim Van den Wyngaert]

Matthias,

You should examine all tcp sockets for keepalive.
If you use a telnet without keepalive, it will hang forever when the other side stops existing.
All applications should request it (also check inet subsystem attribute tcp_keepalive_default to enable keepalive functionality for programs not requesting it).

Wim

[Antoniov.]

Hi Matthias,
on freeware v5 http://h71000.www7.hp.com/openvms/freeware/index.html
you can find a ftp mirror; you can find some inspiration from it.

Antonio Vigliotti

[Matthias Djurkovic]

This was open for too long time now. We had no real idea how to solve the problem, as it reappeared all the time.

Since I have found the hang to suddenly disappear while analysing the process with SDA (at least it seems so) I have now decided to contact support to have them help us.