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[K12OSN] KX7-333R mboard for Athalon Server / Swap Death?



Chip,

Your comments on the KX7-333R intrigued me as a cost effective solution.
The only different configuration I see as favorable would be a mirroring
array - seems a lot more reliable. an 8.7ms seek and ATA/133 oughta rock
on performance.

If swap hampers a system THAT badly - seems like it would be desirable
to DISABLE swap space after packing a large ammount of RAM into the
system - say 128-256mb/Client.  That gets expensive of course, but words
such as "out of the game" and "kill a setup" (someone else used) make it
sound like an unrecoverable crawl.  Couldn't the clients just close some
apps to free up RAM if they get into a swap situation?

K12LTSP 2.0.2 keeps dying installing the Mozilla client 98% through the
install - I got it to go on my 3rd attempt 2 days ago before a
reinstall. The md5 is flawless, checked twice.  I burned a second copy
tonight, but it's too late to do anything else on it.  Will give it a
shot tomorrow.

Hardware for my test station is as follows: (it's my powerbox - doesn't
get as much use since my PIII 1ghz/30gb 15" IBM A30 laptop arrived :) )

Abit KT7A-Raid
AMD Athalon 1.2ghz
WDC model 600BB - 60gb IDE ATA/100
512mb PC133 SDRAM 168pin
2 3C905B-TX 100bT NIC's

I'll letcha all know how it works, not sure when I'll have a chance to
hook more than 2 or 3 clients up to it.  All will be varying hardware
booting from a floppy, so I don't interfere with their current
configuration booting to their existing hard drives.


-----Original Message-----
From: k12osn-admin redhat com [mailto:k12osn-admin redhat com] On Behalf
Of chip
Sent: Monday, May 27, 2002 1:21 AM
To: k12osn redhat com
Subject: Re: [K12OSN] Client RAM requirements? / Athalon ATA server vs.
Dual-Xeon with SCSI - feedback?


I just have one comment on the table you attached.
I would recommend using a different Motherboard, Perhaps the Abit
KX7-333R($105.93 from mwave.com), instead of the Abit KT7A. The newer
Abit Board gives you onboard ATA-133 + Raid 1/0 and 4x DDR Ram Slots.
You could then put in 4 x 512 Mb DDR (CORSAIR CM64SD512-2100 64X64
PC2100 512MB CAS2.5 DDR DIMM)($137.50 ea. from mwave.com).(Giving you 2
Gigs of RAM for your Athlon based Server) Then using the Onboard IDE
Raid, put the two 60 GB Drives in a Striping Array(RAID 0).(Of course --
this gives you NO data backup -- so if a single drives dies, your whole
system is dead :-) )

I don't think using another hard drive as swap will give you any
signifigant performance increase, by the time Linux starts using your
Hard Drive swap for active programs, you are already out the game from a
remote client standpoint.

Anandtech has done a few comparisons of the Xeon vs the Athlon:
http://www.anandtech.com/IT/showdoc.html?i=1606
Their main focus on SMP vs SMP, but they are one of the few places that
attempt to do server benchmarks, not the fastest Quake3 Frame Rates.

I think you will find, Dollar per Dollar, a Athlon based system will
outperform a Xeon based one.(also, you should look at Dual Athlon/Duron
Server if you are serious about putting 24 clients on a server).

SCSI vs IDE -- well, here I will say right out, you get what you pay
for. With the recent fiasco of IBM exiting the IDE Hard Drive Business,
and only rating their IDE Drives for 4 hours a day of use, I would
highly recommend using SCSI, if it fits your budget, however, if not,
using Striped Arrays with IDE, you can get simular performance.


----- Original Message -----
From: Greg Long
To: k12osn redhat com
Sent: Sunday, May 26, 2002 10:09 PM
Subject: [K12OSN] Client RAM requirements? / Athalon ATA server vs.
Dual-Xeon with SCSI - feedback?


I am getting involved with our local schools to explore the possibility
of a K12LTsP deployment. After some initial reading, it appears for
K12LTSP (2.0.2 ISO's just downloaded) almost any old legacy box can
become a client.

My main question is how much RAM is required?  I should think if
everything runs from the server, even 4 or 8mb RAM would do fine, and
even a pentium 75 with a 2mb DRAM PCI video would perform nicely with a
100bT NIC.  We can most likely make extensive use of existing clients.

Attached is some ballparking I did for a single CPU Athalon Server for a
target of 12 clients utilizing 3 ATA/100 drives and a Dual Xeon for a
target of 24 clients.  The prices come from a little poking around on
pricewatch - with the recognition that we may pay a little more in one
area and skimp a little in another.  My thought is that is due to the
larger storage space per dollar (as well as client) the IDE drives might
be a favorable option over the SCSI drives. 8.7ms seek for 12 clients vs
5.2ms seek for 24 clients is the number that really seems to make this
acceptable - plus the estimated cost per client.  I am also figuring
putting a separate 9 or 10gb drive for a swap-only partition should help
out the whole equation.  128mb/client ought to help reduce swapping in
the first place, until client load gets heavy. Certainly a smaller drive
than a 10gb 7200rpm IDE

The Xeon server could also be built more cheaply - such as 1.7 Xeons, or
even a single CPU Xeon.  From the reading, I've been getting the
impression that CPU load isn't really the performance bottleneck, but
rather the RAM and seek time of hard drives.

I'll be setting up a test K12LTSP server soon at home to play with all
this on a 1.2 Athalon /ATA100 drive and 3 or 4 existing Winboxes of
various speeds, booting to floppy to connect to the server - I'm not up
on how to configure those yet for the various Xf86 drivers, but I'll
read the documentation. :)

Another question, on the site, it was mentioned that 2 SCSI drives were
suggested for the larger server - one for /home, although I think in the
example /home was mounted on another server's SCSI.  I'm thinking
putting /home on the same box should not adversely affect performance
too much.

Finally, and this is a bigger curiosity than some of the others: Network
congestion.  Pushing graphics over a 100bT can get slow.  Not being too
knowledgeable about X, my experience with this is limited to running
VNCserver/client over my 100bT here - but I'm the only user. With 24 or
32 active clients, isn't the network a limiting factor? Would
performance be noticeably increased with just 12 clients?

I'd welcome any feedback on these 6 issues as described above:

1) RAM/CPU for clients
2) IDE vs. SCSI
3) Athalon vs. Dual Xeon
4) Separate swap drive - would it help?
5) /home on separate drive on same box
6) Network congestion with 24 or 32 clients vs. 12 clients

Big thanks,

Greg Long
Klamath Linux Unix Group http://www.maneuveringspeed.com/klug/index.html



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