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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
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

Anandtech has done a few comparisons of the Xeon vs the Athlon:
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

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