Re: Xen - Mosix cluster

["Tom Cranbrook" <tcranbrook@australia.edu>]

>
>Since Xen lives at the bottom of the stack, this isn't really possible -
Xen 
>itself is really intimately tied to the specific machine its working on. 
In 
>contrast, Mosix can provide users with the illusion of a big machine but
it's 
>intimitely tied into the Linux kernel.
>
>I don't know so much about OpenSSI, how does that abstract things to the
user?
>
SSI presents a single instance OS environment, one file structure, one name
space, one set of services, one proccess list in /proc , that reflects the
conbined resources of the nodes.  Each node machine is totally assemilated
into the one image. I'm not sure of this, but I believe a node can not even
function as a terminal to the SSI.  It's a headless boot off the network.

In Mosix, each node is running an indenpendent OS environment and its own
set of services.  A remote node only comes into play if any one node maxes
out and migrates one of its processes elsewhere to lighten the load.  Each
node can be a fully functional workstation.



>> This would also allow a high demand 
>> OS environment to grow past the single machine limit.  This might also
help
>> with issues of bringing nodes on and off line.
>
>This leads to an interesting thought though - Xen does accurate resource 
>accounting on what domains have used.  That's one of its strengths.  A
cool 
>idea (although not one that'd necessarily get done) that'd partially
address 
>your problem would be to plug Xend into Mosix's process migration
mechanisms.
>
>e.g. only allow a process migration to another node if the domain owner
has 
>paid enough and then keep track of the resource usage on the remote node
*as 
>well*, so that the total resource usage is known.  One could imagine
creating 
>XenLinux/Mosix domains on other nodes on-demand when the user's virtual 
>machine wants to migrate a compute-intensive process.  (Domains running in
a 
>ramdisk only take a few hundred milliseconds to start, so this is quite 
>feasible).
>
>This way one could get some of the advantages you mention and retain the 
>strong isolation, resource accounting, etc.
>
>I'll have a think about that, since it does sound kinda cool ;-)
>
>Mark
>





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