[Lubuntu] Some PC's or LTSP clients stall during boot at a blank, black screen

[John Hupp]

Read on about Lubuntu 12.10 after this intro: I have been 
troubleshooting a behavior in which many LTSP clients on my Lubuntu 
12.10 LTSP server fail to boot. They stall after the Lubuntu splash 
screen at a blank, black screen.

But one of the PC's that fails to boot as an LTSP client also * has 
enough resources to boot the Lubuntu 12.10 Live CD*, so I tried that, 
and I found that it fails to boot with the same stalled blank, black 
screen after the Lubuntu splash screen.  I left it like that for ~ 15 
minutes to check for an 8-minute stall (which another user reported 
elsewhere), and it didn't budge.

Since Valerio P is troubleshooting (below) what seems like the same 
behavior with LTSP clients on Edu/Ubuntu 12.04 servers, and since I show 
the same behavior also on a Lubuntu 12.10 Live CD, I now wonder if this 
is a *buntu 12.04/12.10 problem related to certain chipsets or video 
chips.  Complicating that observation somewhat, I note this machine I 
just ran the Live CD on had run both Lubuntu and Ubuntu 12.04 without 
such a behavior.

On 12/4/2012 4:16 PM, John Hupp wrote:

 > Valerio Pachera on the Edubuntu list has been troubleshooting what 
seems like the very same problem.  His thread came apart somehow but you 
can see all the posts here: 
https://lists.ubuntu.com/archives/edubuntu-users/2012-December/thread.html
 >
 > He got his clients working *most* of the time by disabling NBD 
compression.  (Undoubtedly performance has taken a hit.)  He refers to 
documentation of a previous problem with NBD compression on fat clients 
which presumably was solved, but now gives the appearance of having 
returned.  See 
https://help.ubuntu.com/community/UbuntuLTSP/FatClients#Reenabling_NBD_compression.  
However, one LTSP gurureplied that it was likely that NBD compression 
was not the cause of the problem, but was merely allow the real cause to 
manifest this behavior.
 >
 > I checked out the NBD compression issue nonetheless.  On my server, 
there was no /etc/ltsp/ltsp-update-image.conf file, but I created one, 
added the NO_COMP line, and updated the image. This did not solve the 
problem with any clients I tested. Though our respective setups are 
different on a number of points, detailed pretty well here: 
https://lists.ubuntu.com/archives/edubuntu-users/2012-December/007206.html

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