[Beowulf] Compute Node OS on Local Disk vs. Ram Disk
kyron at neuralbs.com
Wed Oct 1 14:27:11 PDT 2008
Bogdan Costescu wrote:
> 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".
More or less, NFS-root changes are "propagated" instantly, most other
approaches require a re-sync. Another way to see this, the NFS root
approach only does changes on the head node and changed files don't need
to be propagated and are accessed on a as-needed basis, this might have
significant impacts on large deployments....not that I suggest that they
use this approach ;)
> However random installations or modifications of configuration file
> within the chroot become very difficult to reproduce when you build
> the next node "image"
Document document document...which no one does...but document.
> - 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.
I'll take your word for it that they have a version tracking mechanism.
>> 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" ?
Well, that's what I meant... probably not clearly. ;)
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