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List:       linux-cluster
Subject:    Re: the "cluster" system call
From:       <irbis () orcero ! org>
Date:       2001-07-13 7:13:43
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 Hello, David!

> As I mentioned earlier (months ago) :)
> it could be a mountable fake file system.

 Better focused, something like a /proc filesystem. :-)


 I thing that in that way the Mosix aproachment is a very good idea. Since
all the information is on a subdirectory of /proc, is a really
non-intrusive way to get information and to put orders to the cluster.
(non-intrusiveness is inmportant. I hardly can imagine myself rewriting
some of these molecular dynamics dinnosaurs, and, what is worse,
explaining to the HPB why I am doing this.

 Anyway, you have here a good idea, since:

>
> mount special-file mount-point -t cluster-type
>

 Could be an EXCELENT way to control dinamically the membership of a
machine. If you do:

mount /proc/cluster -t cluster

 you enter on the cluster, and with:


umount /proc/cluster

 you get away the node of the cluster. To enter automatically, is only
having the line:

none /proc/cluster cluster defaults 0 0

 On the fstab.


 (in fact, I always have thought that the most of the code of Mosix could
be reused, and we could work on parching the weakness of Mosix, only for
not to reinvent the weel; this was before the "using XML for
transmitting control information" and "broadcast on ethernet do not hurts
network performance" threads)


> The mount-point would be a directory where all the
> control interfaces, including a standard subset and
> whatever extensions the particular system adds on, will
> live.

 Same as Mosix... I think the same.

> the cluster-type would be the clustering discipline to
> give the special-file to, to set itself up.  Mount might
> be able to figure out what kind it is on its own.

 Maybe, more if we take into account that hp and ha have completly
different objectives. We can keep the same infraestructure -CPIDs, node
tables, and so on- but in the mounting type we choose if we want HP or HA.
Some of the things that HP people says -as the laptop stuff- are anthem
for HA people, and some of the things that HA people says -"broadcasting
constantly XML messages to keep on date membership information" are
somewhat hard to eat by HP people. Thus, we could redefine the mount
before as:

mount /proc/cluster -t HPcluster

 and

mount /proc/cluster -t HAcluster

and with this we enable/disable the features proposed for HA people, or
more Mosix-like features.

> I was about to write a completely user-mode system based
> on unix-domain sockets this spring but got distracted.

 Well, this already exists (PVM), and work fine. Anyway, PVM has its own
leaks, please share with us the fresh ideas that you were going to use on
your user-mode system.

 Yours:

David


---------------------------
     irbis@orcero.org
http://www.orcero.org/irbis
---------------------------


Linux-cluster: generic cluster infrastructure for Linux
Archive:       http://mail.nl.linux.org/linux-cluster/

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