CCL:Largest Linux Cluster? (fwd)

[Craig Tierney]

Saying that 'they use no local disk, opting for a huge disk farm' is
not exactly correct.  All nodes are diskless, and they do have a huge disk
farm.  The san is for data storage, user codes, etc.  The nodes are diskless
because they need to be able to switch parts the machine from classified to
non-classified depending on the situation.  They cannot have any storage locally
to accomplish this.  It doesn't take much disk to boot 1000 nodes remotely. 
All common files are shared, and only some system specific things such as /etc
are generated unique to each node.  I think (not positive) that /var and /tmp
may be small ram disks, but I don't remember exactly.

Does hdparm work with SCSI?  Does it really accomplish much?  I didn't think
it did.  They SAN is scsi, so I don't think they are running hdparm to optimize it.

Craig

On Thu, Jan 24, 2002 at 10:17:28AM -0800, alvin at Maggie.Linux-Consulting.com wrote:
> 
> hi art
> 
> On Thu, 24 Jan 2002, Art Edwards wrote:
> 
> > On Thu, Jan 24, 2002 at 05:55:24PM +0100, Eugene Leitl wrote:
> 
> ...
> 
> > > Can anyone tell me what is currently the largest linux-based workstation
> > > cluster that has been successfully deployed and is being used for
> > > computational chemistry studies?  (largest = number of nodes regardless of
> > > the speed of each node).
> > > 
> > Sandia National Laboratories has C-Plant that runs Linux in addition to several
> > layers of home-grown OS on several thousand nodes. The basic node is a DEC 
> > ev6 with myranet (sp). They use no local disk, opting for a huge disk farm.
> 
> do you happen to know how they manage the huge disk farm???
> 	- resumably raid5 systems...
> 	- are each raid5 sub-system dual-hosted so that the other cpu
> 	can getto the data if one of the cpu cant get to it
> 	- does all nodes access the "disk farm" thru the gigabit ethernet
> 	or dual-hosted scsi cables ??
> 	- how does one optimize a disk farm ?? (hdparm seems too clumbsy)
> 
> -- in the old days.... 1980's ... there used to be dual-hosted
> disk controllers where PC-HOST#1 and PC-HOST#2 can both access the same
> physical CDC/DEC/Fujitsu drives
> 	- wish i could find these dual host scsi controllers for todaysPCs
> 
> have fun linuxing
> alvin
> http://www.Linux-1U.net .. 8x 200GB IDE disks -->> 1.6TeraByte 1U Raid5 ..
> 
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-- 
Craig Tierney (ctierney at hpti.com)