Well Tony,

Things are pretty simple for using SSI at your beowulf cluster.

The short summary:

a) openmosix is dead
b) open-ssi is still alive

Simple tip: go for open-ssi.



A bit longer explanation:

a) openmosix is dead. I can confirm that even wikipedia has that.
Openmosix was an Israeli project and therefore died when It's Israeli main developer left, for whatever reason. He has left a very clear statement that he no longer works on openmosix. What usually happens is that 1 or 2 enthusiasts then do an effort to support it. If that doesn't work for you,
     then consider it dead.

Using kernels 2.4.x is not realistic for todays quadcores. That was the status in 2005, that is in 2008 still the status. In 2005 if i remember well i used kernel 2.6.7 for a quad opteron dual core. Using kernel 2.4.x versus 2.6.x numa gave at a dual opteron dual core a speedloss of 50% for my chessproggie.
50% is *a lot* to lose in speed.

Supporting a thing like openmosix requires a lot more than 1 guy who in order to modify 3 bytes needs 1000 dollar.

What you see a lot is that open source projects get hijacked by people who want to make cash out of it. In the world i come from, computerchess, i remember already since 1988 that this happens every year several times. The developers usually get really demotivated when they work for hundreds of hours at their 'money project', and then just make under a 1000 dollar; at the macdonalds you make more money.

In short such projects usually die soon also, as there is no money for them into it. Most nerds are social seen total robots.

b) open-ssi is there fore several distributions and actively supported by several developers. It is there, it works, it improves and it works for latest kernels also (yes also 2.6.x).

In itself it would be GREAT if there is 1 open source project there, as that joins forces more. My hope is that open-ssi will work great for highend nic's also and slowly get to a phase that all features work great.

OpenMosix nor openssi could migrate processes that work with shared memory, a nerd feature i like personally a lot.

Just claiming that they use 'stolen' features like page migration is like claiming that linux stole multithreading from unix;
it is a bad attempt to smear dirt just to earn a 1000 dollar.

It is not a reason to not use it. It is a bad attempt to spit at these guys who donate time and their money without asking for payment.

Vincent


On Oct 1, 2008, at 1:10 PM, Tony Travis wrote:

Vincent Diepeveen wrote:
I agree tony that paying for such crap is not very good idea.

Hello, Vincent.

I don't think MOSIX2 is crap!

However, I don't like the idea of having to pay for 'updates'.

You might want to move to open-ssi in this case; the project is alive and there is in theory work getting
performed on support for cards over infiniband as well.

I have looked at OpenSSI, which uses the openMosix load-balancer, but process migration is more coarsely grained than in openMosix. Only the active pages of the user context of openMosix processes are migrated.

I've been looking at alternatives and I think Kerrighed looks very promising but, in our hands, Kerrighed is very fragile: I've mentioned on this list before that if one Kerrighed node goes down you lose the entire cluster. We've been talking to Christine Morin's group at INRIA and they tell us that the next release of Kerrighed with be more robust:

        http://www.kerrighed.org

Most importantly is that you are gonna get more replies.

Yes, thanks for yours :-)

Additionally the manner open-ssi implements shared memory is very transparant; in principle on each write it migrates a page
to the node writing.
Maybe the only big lack of open-ssi is its limited support so far for highend network cards.

What bothers me about OpenSSI is that it's based on an open-sourced version HP's (now Compaq) discontinued commercial product "non-stop clusters for Unix". The OpenSSI project also came in for a lot of criticism from the openMosix community for stealing ideas, so my concerns about it might not be all that well founded ;-)

The main reason I didn't use OpenSSI, previously, was that many features had not been implemented fully and, like Kerrighed, it wasn't really a viable option for a 'production' cluster even though it was interesting as a research project. What makes me take MOSIX2 seriously now is that it is a commercially supported 'product' with all the same virtues (and most of the vices) of openMosix.

        Tony.
--
Dr. A.J.Travis, University of Aberdeen, Rowett Institute of Nutrition
and Health, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, Scotland, UK
tel +44(0)1224 712751, fax +44(0)1224 716687, http://www.rowett.ac.uk
mailto:[EMAIL PROTECTED], http://bioinformatics.rri.sari.ac.uk/~ajt
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