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Geoff Jacobs | 1 Jul 2007 04:30
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Re: Resources for starting a Beowulf Cluster (NFS Setup?)

Robert G. Brown wrote:
> On Wed, 20 Jun 2007, A Lenzo wrote:
> 
>> Hello all,
>>
>> I am new to Linux and need help with the setup of my Beowulf Cluster. 
>> Can
>> anyone suggest a few good resources?
>>
>> Here is a description of my current hurdle: I have 1 master node and 2
>> slave
>> nodes.  For starters, I would like to be able to create a user account on
>> the master node and have it appear on the slave nodes.  I've figured out
>> that the first step is to copy over several files as follows:
>>
>> /etc/group
>> /etc/passwd
>> /etc/shadow
>>
>> And this lets me now log into any node with a given password, but the
>> home
>> directory of that given user does not carry over.
> 
> I'd suggest getting a good book on Unix/Linux systems administration at
> your local friendly bookstore.  Most of this is standard stuff for
> managing any LAN, and the one by Nemeth, Snyder and Hein (Linux
> Administration Handbook) is likely as good as any.
> 
> You want to:
>
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Buccaneer for Hire. | 1 Jul 2007 14:55
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Re: Resources for starting a Beowulf Cluster (NFS Setup?)


> What about integrating rsync into the password
> scripts? Fundamentally, I
> don't trust NIS.

>From a security standpoint NIS is not secure and I
don't think anyone would tell you differently.  On the
other hand you don't normally place a cluster on an
unprotected network.

One of the clusters I manage globally is a tiny 34
node HP cluster (SMP dual-core Opteron though) which
is basically a single user cluster kept running at
almost 100% of capacity. There are enough changes
happening this morning that rsyncing, parallel copy,
etc just becomes onerous so I am turning on NIS today
for it.

       
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Mark Hahn | 1 Jul 2007 21:51
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Re: Resources for starting a Beowulf Cluster (NFS Setup?)

> don't think anyone would tell you differently.  On the
> other hand you don't normally place a cluster on an
> unprotected network.

can NIS actually preserve shadow-ness of passwords?  I would 
never run a cluster that exposed encrypted passwords.

> almost 100% of capacity. There are enough changes
> happening this morning that rsyncing, parallel copy,
> etc just becomes onerous so I am turning on NIS today
> for it.

for small clusters, I would definitely use nfs-root;
for larger ones, probably ldap.  having a cron job run 
rsync frequently isn't a terrible solution, though,
especially if there's one canonical node (a login node)
where the only changes are made.
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Buccaneer for Hire. | 1 Jul 2007 23:00
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Re: Resources for starting a Beowulf Cluster (NFS Setup?)

--- Mark Hahn <hahn <at> mcmaster.ca> wrote:

> can NIS actually preserve shadow-ness of passwords? 
> I would never run a cluster that exposed encrypted
> passwords.

I don't include root (or other sometimes critical)
password and let nsswitch handle how it works. The
cluster is segregated from my normal network-and the
login node and monitoring/grid node are the only ones
with access to the cluster nodes and the real world.

> for small clusters, I would definitely use nfs-root;
> for larger ones, probably ldap.  having a cron job
> run rsync frequently isn't a terrible solution, 
> though, especially if there's one canonical node (a 
> login node) where the only changes are made.

Remember for my $DAYJOB I run commercial clusters
where downtime have real implications and a real cost
associated with it.  I build each node stand-alone. 
If an NFS server drops out there is a good chance the
entire cluster won't hit the skids.

We tried using rsync for our kickstart servers and
found that when you are pressed for time you don't
always remember to manually rsync and have to wait
until the normal rsync time.

LDAP takes too much work for a small cluster unless it
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Mark Hahn | 2 Jul 2007 00:14
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interconnects (intel's optical cx4)

this surprised me:
http://www.intel.com/design/network/products/optical/cables/index.htm

seems like a potentially nice solution to me - any guesses about price?

I guess my hope is that these might become somewhat commoditized, and 
thus provide a 10+ Gb media that avoids a pair of $500 XFP's, and yet 
gives thinner/lighter/longer cables than CX4.  (and from what I read,
chances are poor for 10GbaseT to run cool and low-latency enough.)

I especially like the fact that they are agnostic of the difference between
10GE and IB.  but they do draw 1.1-1.2W from the connector - is this
commonly supported?

thanks, mark hahn.
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Gebhardt Thomas | 2 Jul 2007 16:05
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Solved: SATA(?) errors locks up node

Hello,

thank you all for your advice! 
After a Firmware upgrade (->20.06C06) of the SATA disks we had no
further incident until now. So I'm pretty sure that we have caught the bug.

Thanks again, Th. Gebhardt

On Wednesday 23 May 2007 11:13, Gebhardt Thomas wrote:
> we are running a cluster of 57 dual opteron nodes. Once or twice a week
> one of these nodes gets in an error state and can't connect to the
> I/O-subsystem anymore. I need to reboot that node. As far as I can see,
> the problem occurs randomly at any of our nodes, i.e., the MTBF of a single
> node is about 6-12 months.
>
> I still don't know whether this is a problem of the linux kernel sata
> driver, a hardware problem, a flaw of the disk firmware or something else.
> I'm looking for a possibilty to track down the problem without
> substantially interfering with the jobs on the cluster.
>
> This is our environment:
> TYAN S3992 motherboard with Serverworks HT1000+2000 chipset.
> 2 DualCore Opteron  2216 HE 2.4GHz, 16GByte Mem
> Western Digital 250GByte SATA disk, WDC WD2500YS-01SHB0, firmware rev. 
20.06C03
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Robert G. Brown | 2 Jul 2007 17:24
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Re: cold cathode fluorescent backlighting

On Thu, 28 Jun 2007, Joel Jaeggli wrote:

> Robert G. Brown wrote:
>
>> So yes, I think that LCDs are, on average, far better for the planet and
>> your pocketbook than CRTs (remember, an 80W power differential can add
>> up to $100's in power savings over the lifetime of a monitor), but not
>> perfect.  LEDs, if/when they ever appear (Cree, are you listening?)
>> would almost certainly be better than either in all ways.
>
> led backlit displays are already commercially available (for a year or
> more in some case like cellphone and high-end lcd tv), with the new mac
> be a notable but not first example in a laptop. As lumens/watt continues
> to increase their advantages over ccfl's will continue to grow... At the
> same time direct emissive displays (oled) will eventually challenge lcd
> in most areas where lcd currently challenges other technology.

Ah, I hadn't realized LEDs had made it to the street in real computer
displays (as I'm not a Mac person:-).  But I'm quite ready to lose the
tubes in LCDs...

     rgb

>
>>    rgb
>>
>>>
>>>  Wikipedia is a good source of keywords for use in further research. I
>>> would not consider Wikipedia an authoritative source of information on
>>> it's own.
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A Lenzo | 2 Jul 2007 21:45
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RE: Beowulf Digest, Vol 41, Issue 2

Re: NIS

Hello all,

Thank you to Everybody who has been helping with my NFS/NIS setup.  I am
very grateful.  Even though NIS may not be extremely secure, it seems a
decent solution for my small network which is, BTW, behind a firewall.  All
I need is a simple solution.  I have begun setting up NIS - to get it to
work, I changed the yp.conf file to the following:

domain nisbanjosrv server banjosrv
ypserver banjosrv

The problem is that every time I reboot, this file reverts to the following
code instead:

#generated by /sbin/dhclient-script
ypserver 128.??.??.4

----------------------
Now, I can vi the file and fix it, but of course, I'd rather not have to do
it on every reboot. By the way, 128.??.??.4 is another Linux server on my
same network that probably uses NIS also. Don't know how or why this is
being picked up - but this new server (and the nodes it supports) will
ultimately have to be separate even though they will be on the same network.

I tried using chmod 444 on yp.conf in hopes that it would prevent the system
from overwriting it, but this has also not worked.

So the question is: how can I prevent yp.conf from being changed on every
(Continue reading)

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Buccaneer for Hire. | 2 Jul 2007 22:14
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Re: RE: Beowulf Digest, Vol 41, Issue 2


option nis-domain       "XXXXXXX";

--- A Lenzo <alenzo <at> mail.rochester.edu> wrote:

> Hello all,
> 
> Thank you to Everybody who has been helping with my
> NFS/NIS setup.  I am
> very grateful.  Even though NIS may not be extremely
> secure, it seems a
> decent solution for my small network which is, BTW,
> behind a firewall.  All
> I need is a simple solution.  I have begun setting
> up NIS - to get it to
> work, I changed the yp.conf file to the following:
> 
> domain nisbanjosrv server banjosrv
> ypserver banjosrv
> 
> The problem is that every time I reboot, this file
> reverts to the following
> code instead:
> 
> #generated by /sbin/dhclient-script
> ypserver 128.??.??.4
> 
> ----------------------
> Now, I can vi the file and fix it, but of course,
> I'd rather not have to do
(Continue reading)

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Steve Cousins | 3 Jul 2007 17:59
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10 GbE vs. Trunked 1 GbE performance?


We are purchasing a NAS NFS server for our cluster and I'm wondering if a 
10 GbE card would give us twice the performance than say 4 trunked 1 GbE 
lines.  Given that the NAS itself has the performance to drive this, do 
any of you have real-world numbers comparing this sort of thing?

Thanks,

Steve

--

-- 
______________________________________________________________________
  Steve Cousins, Ocean Modeling Group    Email: cousins <at> umit.maine.edu
  Marine Sciences, 452 Aubert Hall       http://rocky.umeoce.maine.edu
  Univ. of Maine, Orono, ME 04469        Phone: (207) 581-4302
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