Users can't connect to Database

Hi all!
I have a problem just few hours ago:
Users call to say the application (that use adabas as a db) it’s freeze, other users call to say they can’t login to the same application. I go to database server and begin to search, first, the server it’s ok, processor is 4%, memory is 40%. After y go to the adaopr to see the user connections, all was aparently ok, go to dbaworkbench and see the high water marks, and i don’t see nothin that can be a problem.
I try to login to the application and it freeze in the moment it try to validate user. The users that was logged in the app freeze when they try to consult somthing. I really don’t know what happend, because there is no error, bla bla bla. Solution for the moment: shutdown database and restart server (time 10 minutes).
Please someone can help me, giving me some tip to what to do in this case, i mean, some tip to see some log, some report, o something that can help me to find out what is the problem?
Thank you for your help and time,
P.D. I’m not a certified neigher dba.
P.D. 2 There is a attachment with the high water marks.

what is the operating system? what is the application built with - Natural, Java, .net, ?? When you say the “users can’t log in” - what are they logging in to? What security is being used?

The database stats look fine. You can check the adanuc.log, but you’re more likely to find the issue within the application and the login process than on the database.

Sorry, forgot that important information:

  1. Windows server 2008. Adabas 6.1.9
  2. The application uses Natural as a backend and Vb6 as a frontend. It uses DCOM to connect to the Windows server.
  3. Logging it’s when they put their credentials in the application, then the app connect to the Adabas for validate user rights, etc.
  4. I check the adanuc.log, but there is no error or an issue message.

Thanks, Douglas.

You have several components in the mix - Adabas is the last piece that is involved. Prior to that you have VB6, DCOM, Natural then Adabas.

Do you have application logs for each step? Is DCOM used to call a Natural RPC Server? - if so, there is a trace there that can be turned on.

Have you checked your Adabas Hold Queue when the issue occurs? Have you tried decreasing the Transaction Timer (TT) when the issue occurs to see if users get a response code 9 (timeout)?

That you can access Adabas from the workbench suggests that the database is not hung, so the issue is something from the application. Has anything changed in the application recently? or the networks it is hosted on?

Thanks Douglas, I’ll try to see all that things.