[NBLUG/talk] thought I'd ask here also - Anyone have any experience with LTSP?

[gandalf at sonic.net]

It's reportedly Gigabit. I'm rather new here so I'm learning as I'm 
going. There is a three LTSP cluster setup and a separate server with 
the /home share which is about two terabytes. There are about a hundred 
forty LTSP users but perhaps 40 of them are currently active. The client 
LTSP machines seem to be Core2 Duos 3ghz with 2gigs of memory although I 
haven't seen all of them. They are running Ubuntu 12.

We experienced some system slowdown today with the load average going 
into the 30-60 range and CPU running to 50% or so if I remember right. 
The two main culprits were chrome and firefox. I did some 
experimentation afterwards while the users were at a party and I was 
able to push the system to about 3 all by myself by watching youtube 
videos or scrolling facebook. Ten bored people checking facebook or 
watching videos could easily produce the results I observed.

I'm thinking about experimenting with turning the thin clients into fat 
clients where they run applications on their own CPUs and memory but 
have only a day or two experience with LTSP. I also think that it's 
rather odd to have the home directories on a separate server. Unless it 
was a dedicated network connection it would compete with the 
server/client connection for bandwidth in a game where everyone looses. 
It would make much more sense to have some sort of fast raid array set 
up directly to the LTSP server.

I'm the new guy on the job here and there is a lot of stuff that was set 
up by people who no longer work here.


On 2015-01-23 16:00, Jordan Erickson wrote:
> Can you give us a bit more detail as to your network/server setup? You
> say you're running 24cpus and 128gigs. Might be a logical explanation 
> to
> house NFS on its own server.. What's your network speed? Thin (or fat)
> client specs? Distro?
> 
> 
> Cheers,
> Jordan
> 
> 
> On 01/23/2015 03:52 PM, gandalf at sonic.net wrote:
>> It's actually a NFS to a separate server. I'm not sure why it was done
>> that way. To me this would probably further congest the network while
>> not being nearly as fast as a high performance direct disk interface.
>> 
>> On 2015-01-23 15:00, Omar Eljumaily wrote:
>>> Not speaking from experience with LTSP server, but my guess would be
>>> that it is a disk io bottleneck.
>>> 
>>> http://stackoverflow.com/questions/21617500/understanding-load-average-vs-cpu-usage
>>> 
>>> 
>>> I believe that web browsers cache on disk most of their content and
>>> media before rendering it.  That's a lot of users hitting a single
>>> disk drive or array.  Do you have a large RAID array?  SSD?
>>> 
>>> Omar
>>> 
>>> On 1/23/2015 2:19 PM, gandalf at sonic.net wrote:
>>>> 
>>>> I'm seeing very high load averages with low CPU usage. The two main
>>>> culprits are chrome and firefox. I've got about a hundred users
>>>> sharing the LTSP server which has some rich resources (24cpus and
>>>> 128gigs).
>>>> 
>>>> 
>>>> 
>>>> 
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