Hi Doug
Consider disk for:
A) swap space (say, if the user programs are large,
or you can't buy a lot of RAM, etc);
I wonder if swapping over NFS would be efficient for HPC.
Disk may be a simple and cost effective solution.
B) input/output data files that your application programs may require
(if they already work in stagein-stageout mode,
or if they do I/O so often that a NFS mounted file system
may get overwhelmed, hence reading/writing on local disk may be preferred).
C) Would diskless scaling be a real big advantage for
a small/medium size cluster, say up to ~200 nodes?
D) Most current node chassis have hot-swappable disks, not hard to
replace, in case of failure.
E) booting when the NFS root server is not reachable
Disks don't prevent one to keep a single image and distribute
it consistently across nodes, do they?
In any case, I suppose you could both have disks and boot with NFS root.
But if you have disks, is there really a point in doing so?
I guess there are old threads about this in the list archives.
Just some thoughts.
Gus Correa
Douglas Guptill wrote:
Ah Ha. I see the point of a non-diskful, or nfs root, install for the
compute nodes. One image to update/change, instead of a whole bunch.
Thanks,
Douglas.
On Fri, Jul 09, 2010 at 07:11:18PM -0400, Mark Hahn wrote:
well, the thing about nfs root is that there's almost no installation,
per se. if you wanted, you could boot the nodes off a live master's
root filesystem. normally, master and node images are kept mostly
separate, though, because it's handy to avoid entangling them
(ie, you may not want mysql-server installed on compute nodes, but only
on the master, etc. or just different versions.)
And from Steve Crusan:
As for the diskfull install, netbooting and statelite (NFS root) solutions
are very easy to scale and customize. Diskfull installs seem to be less
flexible in IMO.
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