[Samba] Transfer rate on NT/XP/2000 with service pack 6a

Berry van Sleeuwen berry at hakker2.demon.nl
Wed Oct 16 18:37:00 GMT 2002


This is not quite a remark on SAMBA, more a report of a problem that is
not related to SAMBA. However it could be of concern to your developers

At our company we recently (last week) installed two new fileservers.
The next thing we got was a very strange effect.

The configuration:

- Two fileservers, running (i believe) Windows 2000, with service pack
6A and included all service and patches currently available.
- Two servers running Sterling Connect Direct.
- Several other NT servers and workstations running NT 4 with
servicepack 6.

The Connect Direct servers are used to transfer data from and to our
mainframe. The data can be located anywhere on a fileserver within our
LAN or even WAN.

After the new fileservers were installed the data-troughput dropped from
several MB per second to bytes per second. A file download from
mainframe to LAN would take some seconds before, now it takes up to
hours! However, an upload was no problem. We checked the connect direct
servers and discovered that the only servers it would have a problem
with were in fact the two new ones. No problems were found when the data
was transferred to the old servers or workstations. Also when the files
were transferred to the Connect direct servers itself there was no
problem. When the file afterwards was to be moved from the CD-server to
the LAN normal speeds were recorded. So only when transferring directly
from mainframe to LAN, by the CD-server, was a problem.

At this stage we have received a message that the SMB protocol has been
changed. It was discovered that it had a serious security leak that has
been 'repaired' with the most recent fixes. We don't know what has
changed, but it seemds that there is some kind of checking on the
transfer that will lead to a serious drop in the transfer rates. My
guess would be that if there is a non-windows environment involved in
the datatransfer it will be treated in a 'very safe' way, and by this it
cannot get a normal transfer rate.

Actually, well I'm a mainframe guy, I don't want to know what has been
changed. To me, windows is one giant security leak but anyway. I imagine
this could be of interest for those who have an interrest in the SMB
protocol. If this is true for a mainframe connection it very well could
be true for some *nix connection too. We do not use unix in our shop,
nor SAMBA so we can't test this one. At home I've used SAMBA a few times
to get my Linux connect to my Windows system. It has never been setup
properly, I only used it to get some files from my windows to my linux
without using FTP.


Berry van Sleeuwen.

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