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Subject: Re: [OMPI users] How does authentication between nodes work without password? (Newbie alert on)
From: Tena Sakai (tsakai_at_[hidden])
Date: 2011-02-13 17:16:08

Thank you, Ashley, for your comments.

I do have a question.
I was using 'sudo su' to document the problem I am running
into for people who read this mailing list, as well as for
my own record. Why would you say I shouldn't be doing so?



On 2/13/11 1:29 PM, "Ashley Pittman" <ashley_at_[hidden]> wrote:

> On 12 Feb 2011, at 14:06, Ralph Castain wrote:
>> Have you searched the email archive and/or web for openmpi and Amazon cloud?
>> Others have previously worked through many of these problems for that
>> environment - might be worth a look to see if someone already solved this, or
>> at least a contact point for someone who is already running in that
>> environment.
> I've run Open MPI on Amazon ec2 for over a year and never experienced any
> problems like the original poster describes.
>> IIRC, there are some unique problems with running on that platform.
> None that I'm aware of.
> EC2 really is no different from any other environment I've used, either real
> or virtual, a simple download, ./configure, make and make install has always
> resulted in a working OpenMPI assuming a shared install location and home
> directory (for launching applications from).
> When I'm using EC2 I tend to re-name machines into something that is easier to
> follow, typically "cloud[0-15].ec2" assuming I am running 16 machines, I
> change the hostname of each host and then write a /etc/hosts file to convert
> from hostname to internal IP address. I them export /home from cloud0.ec2 to
> all the other nodes and configure OpenMPI with --prefix=/home/ashley/install
> so that the code is installed everywhere.
> For EC2 Instances I commonly use Fedora but have also used Ubuntu and Solaris,
> all have been fundamentally similar.
> My other tip for using EC2 would be to use a persistent "home" folder by
> renting a disk partition and attaching it to the first instance you boot in a
> session. You pay for this by Gb/Month, I was able to use a 5Gb device which I
> mounted at /home in cloud0.ec2 and NFS exported to the other instances, again
> at /home. You'll need to add "ForwardAgent yes" to your personal .ssh/config
> to allow you to hop around inside the virtual cluster without entering a
> password. The persistent devices are called "Volumes" in EC2 speak, there is
> no need to create snapshots unless you want to share your volume with other
> people.
> Ashley.
> Ps, I would recommend reading up on sudo and su, "sudo su" is not a command
> you should be typing.