2008/12/1 Oliver Grawert <[EMAIL PROTECTED]>
> hi,
> Am Samstag, den 29.11.2008, 11:27 +1300 schrieb Krsnendu dasa:
> > 2008/11/29 David Van Assche <[EMAIL PROTECTED]>
> >
> > On Wed, Nov 26, 2008 at 4:33 AM, Krsnendu dasa
> > <[EMAIL PROTECTED]> wrote:
> > > If you install more programs to run locally doesn't that
> > make the image
> > > bigger?
> >
> >
> > The image is bigger, sure, but it's still being loaded from
> > the
> > server, and there is no relation between image size and ram
> > usage...
> >
> > I thought the image was loaded into a ramdisk on the thin client?
> no, it is mounted from the server. during boot of a client a tmpfs is
> created in ram for the writeable system bits needed to run the client
> system (this includes system bits of local applications if they run
> indeed)...
>
> in case of local applications, the users /home is additionaly mounted
> via sshfs so that user data goes onto the server right away.
>
> the growth of the image is really a minor factor here, the normal ram
> usage of the app and how many bits it writes in the system area are the
> more importat factors.
> userspace apps rarely use much space in the system area i.e. in case of
> firefox for example all the cached data goes into the users homedir
> (though downloads and flash movies will be cached in /tmp).
>
> Thanks for clarifying.
So to compare
1. Local install:System stored and run from local hard drive. All processes
run by local CPU using local RAM. May mount home directories from server.
2. Low fat (DRBL) clients. System stored and run from Server harddrive, but
writeable system bits are stored in a ramdisk on the client itself. All
processes run by local CPU, using local RAM. Home directories mounted from
the server.
3. Thin Clients with local apps: System stored and run from Server
harddrive. The system filesystem is mounted from the server over the
network. All processes run by server CPU, using server RAM, except for basic
input output services and local apps which run on local CPU and RAM.
(Writeable system bits for local apps are stored in a ramdisk on the client
itself.) Home directories mounted from the server.
4. Thin clients: System stored and run from Server harddrive. The system
filesystem is mounted from the server over the network. All processes run by
server CPU, using server RAM, except for basic input output services which
run on local CPU and RAM. Home directories mounted from the server.
So with low fat clients and local apps the advantage is running an
application with local cpu and ram as opposed to server cpu and ram and the
lag associated with it. Is there any lag because the system is reading from
a network drive rather than a local drive? In the case of the multimedia
apps I was trying to run, I thought that some of the lag was due to
accessing the media files, but if the app and the files are on the same
server, the lag must be caused by a delay in sending the audio to the
client. In this case, local apps or low fat client might improve the
situation.
In relationship to this, can you explain the difference between nbd and nfs
for LTSP. As I understand nbd compresses the system image, whereas nfs just
directly mounts the filesystem. I thought that this was used to download a
simplified system image to the ram of the client. Can you please clarify
this a bit more?
Thank you for taking the time to clarify. I hope that clarifying this for me
will also be helpful for others who are confused. I don't think I am alone.
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