Doubts on Windows Media Load Simulator

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Helder - 22 Jan 2004 21:17 GMT

Hi,

I'm currently running tests using Windows Media Load
Simulator Series 9. But there is one weird thing going on
that I'm not able to understand and I hope somebody could
help me with that.

The test is being conducted using 2 computers. Both
computers (server and client) are very fast (the
specifications are below). They're not on a local LAN, so
the IPs are from the public internet. However, both are
located in a very, very large datacenter, with a 100 Mbps
connection each. Pretty fast.

In theory, these computers would easily handle a couple
of hundred simulations (I'm doing WMV simulation with
100kbps streams). When I simulate 100 clients, it runs
smoothly. However, when I run 200, it shows
several 'Failed to Open' erros, claiming that 'There is
no connection established with the Windows Media Server'.
A couple of seconds later, the problems stop happening
and the simulation reaches the expected number of clients
(200).

Now, isn't that strange? Why wouldn't there be a
established connection, if the server is up and running?
Please keep in mind that the server is being used only
for this testing. It's still not being used by users yet.

And more: if there is a connection problem, why do the
total streams number reach the 200 after a few seconds?

In other words: what do these erros mean?

Just another information: while the testing was being
made, I had a look at the server performance. The
processor never went above 5%, which leads me to think
that this is being very easily handled.

Here are the specifications of the computers:

THE SERVER
Windows 2003 Server Standard Edition
Windows Media 9
Dual Intel Xeon 2.66
2GB RAM
5 x 36 GB SCSI RAID 5

THE CLIENT
Windows 2003 Server Standard Edition
Intel Pentium 4 2.66
512 RAM

I do appreciate you help and thank you in advance.

Helder

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Jeremy - 22 Jan 2004 22:02 GMT

By default, WMS will only allow 50 connections/sec max. More than likely the
Load Simulator is attempting more than that max per second and the server is
denying them, causing that error. After a few seconds, the LoadSim probably
retries the connection attempt, and then repeats the whole process until it
has a total of 200 concurrent connections to the server.

Hope that helps.

-jeremy

> Hi,
>
[quoted text clipped - 52 lines]
>
> Helder

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Helder Conde - 23 Jan 2004 10:20 GMT

Jeremy,

Thanks for the answer. I wasn't aware of that
limitation. Although it seems to explain the problem (in
fact, it did solve the problem when I limited the maximum
number of connections to 50/sec in Windows Media Load
Simulator), there is one thing I still don't understand.

My initial tests were being made with 200 users.
However, we do expect to reach above 800 simultaneous
users. So I started increasing the numbers. Please
remember I'm using 100k/sec streams.

In Windows Media Server, I increased the
parameter 'Limit connection rate (per second)' from the
default 50 to 900 connections. But despite that, when I
run Load Simulator with 800 users, a great amount of them
still have problems connecting in the begining, but
eventually, after a couple of seconds, the number of
connected clients reaches 800.

My question is: would this 800 number be too high for
the client to handle? Am I creating an surreal scenario,
in which 800 simulateous people try to access content at
the very same second? As surreal as it may be, the server
doesn't even get his feet of the ground to accomplish
this transfer: the processor stays at 3% only. Would the
problem be on the client?

One final question: in your experience, what should be
the maximum stress on the server in a real-world
environment, in terms of network and bandwidth use
percentage? 50, 60, 70%?

I know I'm asking a whole lot a questions, but I do
count on your expertise and kindness.

Regards,

Helder

>-----Original Message-----
>By default, WMS will only allow 50 connections/sec max. More than likely the
[quoted text clipped - 65 lines]
>
>.

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Tim 'StreamingMeeMee' Carter [MVP/Digital Media] - 30 Jan 2004 14:18 GMT

Did you maintain the 50 new connections/s setting on the LoadSim?

Keep an eye on your network interfaces; utilization, packet send queues,
dropped pkts, etc. If your connection path to the server includes ANY
shared elements (ie, both your machines are not directly connected to
the same switch) you have to contend with other traffic on the wire.
Anytime you push Ethernet above 70% utilization things can get 'funky'.

I haven't used the LoadSim in awhile -- have they updated it to include
the FastStart feature? If so, your server could be pushing a ton of
data, way more than 100kbps, to those first few hundred streams.

Last thought -- If this is an on demand clip, not live, is it stored
locally on the server? I've had issues with highly loaded servers
choking because the clips were stored on network shares rather than a
local HD. A FC storage array fixed that problem. ;-)

Hope this helps.

T.

> In Windows Media Server, I increased the
> parameter 'Limit connection rate (per second)' from the
[quoted text clipped - 3 lines]
> eventually, after a couple of seconds, the number of
> connected clients reaches 800.

Signature

Tim Carter / StreamingMeeMee
Frontier Digital
PH: 508.982.4800
AIM: streamingmeemee MSN: streamingmeemee@hotmail.com
Microsoft Digital Media MVP 2002-2004

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reinstalar o som do windows media player - 25 Jan 2004 12:34 GMT

>-----Original Message-----
>Hi,
[quoted text clipped - 54 lines]
>Helder
>.

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