I have a problem that is not show-stopping, but annoying nevertheless.
Perhaps the smart people here can give me a hint as to what's going
on.

Network:
15 HP thin clients
1 Ubuntu 9.04 x86_64 server running on ESXi with 1-core virtual Xeon
5250, 1GB RAM, GBE
Windows Server 2008 on ESXi with dual-dual Xeon 5250, 12 GB RAM, GBE

If I boot a single tc at one time I see what looks like a normal boot
and the Windows logon screen appears within a minute. However
occasionally, or always when booting more than one tc simultaneously,
the progress bar on the Ubuntu splash screen will stall around 20%,
then the splash screen will give way after a few seconds to a text
console, where I see the following:

Disconnecting: que, disconnect, sock, done
Negotiation: _

And then after some period of time the tc finishes booting normally
and all is well. The delay is approximately equal to 1 minute per
extra booting client. In other words, if I reboot all 15
simultaneously, it is generally about 15 minutes before all are back
at the login screen.

My first suspicion for bottleneck was disk access, although it didn't
really seem like a huge load for a server with an 8-SAS RAID5 array. I
tested this hypothesis by mounting /opt/ltsp/images as a ramdisk and
copying i386.img into it. Now I see a network activity spike on the
server when clients are booted, but no disk activity, as expected, but
the delay is the same.

Likewise, the CPU (top) and network (gnome system monitor, ESXi)
actually read idle during this group boot, but the observed delay
remains the same. Flow control is off on the server and switches,
although it shouldn't matter because the network is passing <1mbit
during this delay.

What do you think could be happening? There is definitely a
peer-dependent delay when booting these thing. There must be some
contention going on during a mass (>1) boot, but I don't know where
else to look. Any ideas?

db

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