[Udpcast] excellent transfer rates (kind of)

Eric Becker Eric.Becker at wwt.com
Tue Oct 14 21:34:27 CEST 2003

I have an HP server that I'm going to use as an imaging server.  It's a
2.8GHz Xeon with a gig of ram and 5 scsi hard drives in a raid 5
configuration.  I have a number of new Dell desktop PC's that I'm going
to be imaging.  They're P4 2.4 GHz w/ 1 80gig 7200 rpm ide hd and 512 mb
of ram.  The network we're using is isolated.  We're using a cisco 6509
as the main switch with a gig uplink to the server.  From there, we ran
4 network drops to where we image the desktops.  Each drop has an 8 port
linksys 10/100 switch and the desktop(s) to be imaged are hooked up to a
linksys switch.  

Here's what I have done to create an image on one of the Dell's

1) Zero out the hard drive dd bs=1024k if=/dev/zero of=/dev/hda

2) install windows xp on the system.

3) reboot the dell with the udpcast floppy image.  I'm using an e1000
driver.  I tell it to ghost /dev/hda.  I choose lzop compression with no
additional parameters.  I then start the udpcast program as the send and
it waits for the reciever (my hp server) to start.

4) start udpcast on the server.   time udp-receiver -f dell_lzop.img  
The server starts and tells me that it has found a client so I hit enter
again and the transfer starts.  

The transfer averages about 15 mbits/sec at first.  After about 5 min it
starts dropping to around 1.6 mbit/sec.  When it's the finished, the
size of the image is just over a gig.  The transfer takes about 30 min. 
Slice % on the sender ranges from .1% to .2% with a few intermittant

Then to send the image back out to another dell PC.

1) boot up dell PC with udpcast floppy.  I tell it to image /dev/hda. 
I'm still using the e1000 driver.  I tell it to use lzop compression and
set it up to be the receiver with no additional parameters.  

2) start udpcast sender on the HP server.  time udp-sender -f
dell_lzop.img --half-duplex --max-bitrate 500m and hit enter.

The transfer runs at over 80 mbits/sec for about a minute and a half and
slows down after 680 mbytes of the 1 gig image have been transfered. 
That's 2/3 of the image is transfered in a minute and a half!.  But then
the transfer slows to a crawl of about 600 kbits/sec.  Once it slows
down, the sender get's constant timeouts with a couple transmits in
between. The slice % is around .3.  The total image time is 71 minutes. 

Anyone have any ideas on what I can do to keep this slow down from
happening?  I'm pretty sure I've ruled out the network as the problem. 
I tried doing a udp-sender -f /dev/zero and udp-receiver -f /dev/null
and I can sustain 85+ mbits/sec for an indefinate amount of time on our
100mbit network.  Are there any switches I should be throwing on the
dell pc to keep it from bogging down when writing the image to the hd?

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