SMB returns the entire file instead of header info
- by billdlawson
Starting a section of code checks for access to many data files (flat files so each table is a file) and when I do a packet capture, in our capture only the header info is sent by the server to the client. However I have one Customer who is using a SAN that gets the whole file instead of just the header info,and besides just being slower, this is causing file access issues. They have already turned off OPLOCKS at the server and at the workstations. This is not client server. The data files and the application reside on the server but the users run the application locally via a shortcut with a mapped drive or UNC.
So when I simply select an option that prompts for a vehicle number, not tryng to select a record but rather simply verify the datafiles are accessible, that window opens in 1-2 seconds for me. When they do the same thing it takes 6-15 seconds after there several users are running the program. Maximum number of users is 15. The program has a lot of small modules, 800 .cob modules. So it is very chatty but these are datafiles.
We have Wireshark captures that show he's pulling the whole file and we're just getting the header. Thier capture vs ours. We suspect the SAN.
Has anyone ever heard of a SAN improperly interpreting runtime requests? So an SMB request.
This is Acucobol-GT (now Microfocus). The application is written in COBOL. This is not a new program just a new problem. This is one customer of over a thousand who are otherwise running smoothly and we are totally stumped.
All XP users, the server is Windows 2003 (with Virtual server) and I don't yet know the SAN info. Also we have many installations running virtual servers but only few on SANs or we just don't know it. This is not a network throught put issue, the load is less than 5% on the server and theer are no timeout or retransmits.
PS If it wasn't for Wireshark I'd still be chasing my tail. An application trace file on thier installation just looks like they run slower. If you want the Wireshark trace file I can make it available.
Thanks in advance - Please excuse my verbosity (word?) but I'm not sure what's relavent.
