OT: Problem with IIS6 and RDS
From: Brian Muth (bmuth_at_mvps.org)
Date: 03/22/04
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Date: Mon, 22 Mar 2004 10:53:27 -0800
Knowing there are a lot of smart people here, I'm bringing this this problem
to the attention of this forum for ideas and suggestions.
There appears to be a problem with how IIS6 works with RDS (yes, I know it
has been deprecated, but there are lots of implementations out there...).
Here are the relevant postings from Baranov Nikolay [NBaranov@BCC.RU] from
the microsoft.public.data.ado.rds newsgroup:
** post 1 **
Two Windows boxes with identical COM objects and databases for comparing and
testing purposes (2000 and 2003) exists as virtual mashines on one big host
server. Network settings for these machines are identical (except IP
address, of course).
We have on remote client request executing time (getting 3000 rows from DB ~
1.4 Mb amount - measured via Network Monitor) about 3 sec on Windows 2000 VM
and 50 (!) sec for 2003 VM. For local request both time are identical and ~
1.5 sec.
Without using RDS both machines have similar responce time for remote client
characteristics, so the root of problem is RDS.
** post 2 **
We used Windows Network Monitor for capture all traffic between server and
client and tried to analyse IP packets for explanation this behaviour.
In short,
1. all data volume getting the client uniformly distributed on all response
time, so performance monitor send bytes report at one short peak in the end
of query is WRONG.
2. Data exchange take place in following manner:
each cycle begins from IP client request packet to server, immediatelly
after that occur HTTP server reply (some packets according max packet size
is 1500 byte) and WAITING time until next cycle begin. The cycle length is
200 ms EXACTLY.
Why client wait almost 200 ms to next request, it's a big mystery for me.
Analogous monitoring for IIS5 shows that WAITING time for client requests
don't present and the same data amount goes to client rapidly (1-2 sec).
Some additional info:
We tested our configuration in two variants (data amount about 1.5-2 Mb)
First, getting recordset on server from SQL server directly. Second, using
COM+ object as middleware between IIS and SQL server. In second case, we
COM+ can monitor method executing time and DTC transaction time. These times
are short (about 1 sec), so all delay time is IIS + RDS ownership.
In addition, if you turn IIS6 to IIS5 isolation mode, RDS work (in first
variant) rapidly as under IIS5. In second case, we can not achieve this
configuration working due error.
Anybody have such problem? How to configure RDS on Windows 2003 to avoid
such strange behaviour?
** post 3 **
Hi!
We found the workaround for this problem.
In TCP settings on CLIENT computer need to add next DWORD value
TcpDelAckTicks and set it to 0.
Extraction from "Microsoft Windows Server 2003 TCP/IP Implementation
Details" article URL
http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/networking/tcpip03.mspx
TcpDelAckTicks
Key: Tcpip\Parameters\Interfaces\interfaceGUID
Value Type: REG_DWORDnumber
Valid Range: 06
Default: 2
Description: Specifies the number of 100-millisecond intervals to use for
the delayed-ACK timer on a per-interface basis. By default, the delayed-ACK
timer is 200 milliseconds. Setting this value to 0 disables delayed
acknowledgments, which causes the computer to immediately ACK every packet
it receives. Microsoft does not recommend changing this value from the
default without careful study of the environment.
After rebooting the connection speed increased more than 20 times (!).
But the question is: We change entire TcpIp settings for client machine. How
this can affect other applications and network functioning in intranet
network?
And how to implement this setting to a lot of client machines?
Any comments?
Brian Muth (MVP VC++)
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