[Beowulf] cluster toolkit comparison questions

Joe Landman landman at scalableinformatics.com
Fri Jul 29 19:35:36 PDT 2005

Hi Andrew:

Andrew Fant wrote:
> Afternoon all,
>    I am in the process of making some assessments for architecture on a 
> new cluster we are building and I have a couple of questions comparing 
> OSCAR vs. Rocks. I certainly don't mind having other options presented, 
> but diskless options like warewulf are already precluded because of 
> administrative fiat.

Warewulf is a good kit, and the developers are good folks (very helpful 
and responsive).  It is a shame that they would be excluded a-prioi.

> 1)  How well can Oscar or Rocks be integrated with an LDAP directory? Do 

Oscar:  can be done, though some hacking of the setup scripts would be 
required.  You would need to package these settings.  Bernard Li is on 
this list, so he should be able to give you a rough guess at how hard.

Rocks:  uses its own system, 411, by default.  It is not impossible to 
change it to another (I use NIS when customers request it).

Generally if you can do the surgery yourself and get the needed packages 
on there (pam_ldap), you should be able to do this for authentication.

> either of them have some mechanism already available for proxying LDAP 
> queries?  On our current cluster, we have had to maintain a local 
> password/group repository, which is something that management has been 
> less than happy about, given the investment they have made in enterprise 
> directory services.

There are some migration scripts to take NIS/files to LDAP.

> 2)  Does Oscar and/or Rocks have support for multiple head nodes?  I've 

Oscar: not the earlier releases as far as I know, I haven't played with 
the latest yet.

Rocks: No (sort of).  Rocks lets you define new appliance devices.  You 
can create a login appliance, and build that.  You will likely need to 
hack the scripts and setup a bit to have this "automated".

> been in the habit of using 2 head nodes, one for administrative 
> functions, and one for user access, and would really like to maintain 
> this practice.  It keeps the administrative tools out of the sight of 
> users, it gives me a second gateway into the cluster for redundancy of 
> access, and it makes it harder for users to accidentally interfere with 
> administrative functions by starting processes on the head node when 
> they "forget" that they aren't supposed to.
> 3) Does either toolkit have problems with home directories coming off 
> from a separate NFS appliance instead of living on a filesystem on the 
> head node that gets exported to the compute nodes directly from there?

Oscar: No.

Rocks: Yes.  This is a design issue with Rocks in that they mount their 
installation directory as /home/install (automounted from 
/export/home/install), and their scripts (as of 3.3.x) still had 
hardwired /export/home/user settings which made it difficult at best to 
feed directories from NASes.  We created workarounds for this for our 

Rocks 4.0 is better than 3.3 with regards to some of these issues.


> Thanks for you help,
>         Andy
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Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
web  : http://www.scalableinformatics.com
phone: +1 734 786 8423
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