Re: another laundry or shopping list

[Lars Marowsky-Bree <lmb@suse.de>]

On 2001-07-16T21:32:01,
   Jordi Polo <mumismo@wanadoo.es> said:

> I agree we double the chance of fail but this about issues you can't take 
> away home node. You need some of the home node syscalls. Think in a 5 nodes 
> cluster,all of them connected with his own modem to internet.  2 of them with 
> telnet and ftp open, as the processes has that sockets open you need a little 
> of it being bound to that node. 

You cannot migrate a process which is tied to a node because it is utilising
node-local (ie, non-shared, not-cluster-aware) resources like a serial line.

That is quite a sensible restriction.

Or you would migrate it away, and _if_ the node doing the serial IO failed, it
would receive IO errors on that file, but the application would continue to
run despite this.

> will be all the machines in the cluster have the same time ? maybe you don't 
> want it and you want the time of your home node not others.

Un-synchronized time is really evil. You want synchronized time. (Note that
this is totally different from the _timezone_ setting)

xntpd is a good starting point.

Eddie/Erlang apparently has a time mechanism which guarantees cluster-wide
synchronized time, which is monotonously increasing. (They compensate clock
offset to the reference clock by making it tick a _little_ bit slower or
faster - really neat)

Sincerely,
    Lars Marowsky-Brée <lmb@suse.de>

-- 
Perfection is our goal, excellence will be tolerated. -- J. Yahl


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