[Beowulf] Compute Node OS on Local Disk vs. Ram Disk

[Bogdan Costescu]

On Tue, 30 Sep 2008, Eric Thibodeau wrote:

> This has given me much flexibility and a very fast path to upgrade 
> the nodes (LIVE!) since they would only need to be rebooted if I 
> changed the kernel. I can install/upgrade the node's environment by 
> simply chrooting into it and using the node's package manager and 
> utilities as if it were a regular system).

Only the first is an advantage of using NFS-root; the second is shared 
by most methods that use a node "image". However random installations 
or modifications of configuration file within the chroot become very 
difficult to reproduce when you build the next node "image" - either 
scripting everything or using cfengine/puppet/etc. can save a lot of 
time in the long run, despite the initial effort to set up.

> But I am in a special case where, if I break the cluster, I can fix 
> it quickly and I always have a backup copy of the boot "root" image 
> ready to switch to if my fiddling goes wrong.

Why not keeping several "images" around and only point the nodes to 
mount the one considered current or "good" ?

-- 
Bogdan Costescu

IWR, University of Heidelberg, INF 368, D-69120 Heidelberg, Germany
Phone: +49 6221 54 8869/8240, Fax: +49 6221 54 8868/8850
E-mail: bogdan.costescu at iwr.uni-heidelberg.de