[luau] LTSP hardware

MonMotha monmotha at indy.rr.com
Wed Jun 12 19:26:01 PDT 2002


Comments inline.

Warren Togami wrote:
> The cheapest server with this capability would be a dual Athlon with 2-4GB
> of Registered ECC DDR SDRAM.
> 

These kinds of systems are mega-powerful, and unless you have lotsa 
people doing lots of stuff all at the same time, it should probably be 
sufficient.  This is also the biggest machine you can build/buy without 
having to go to really expensive quad machiens (which is currently the 
domain of the Intel Xeon processor and things like the IBM Power and 
Alpha archetectures).  One of the nice things about X remote display 
though is that it is mostly (completely?) archetecture indepenendent. 
You could have something like a small Sun (small by comparison to other 
Sun stuff...) or big IBM or Alpha box remote displaying to normal Intel 
systems.  Unfortunately, this does restrict you to mostly OSS software 
since commercial binaries are usually only for x86 (or maybe PPC if 
you're lucky).

A good way to find out what you need would be to have, say, 5-10 people 
use a desktop for what you're looking at, add up the loads at one time, 
then multiply to get the number of clients you'll have.  This will 
probably be the maximum of what you'd ever need, but it's always better 
to be a little over powered than be under powered as you don't want 
people complaining about slowness, and you want to be ready for future 
software that may be more CPU/RAM hungry.

> http://www.amdmb.com/article-display.php?ArticleID=183
> Something like this motherboard.  Several different brands are available
> other than Tyan.
> 
> http://www.crucial.com/store/PartSpecs.asp?imodule=CT6472Y265
> Something like this RAM, although you would need to go with brands other
> than Crucial in order to get larger than 512MB sized DIMMs.  You can fit
> four of these cheap Crucial DIMMs into the Tyan motherboards for a
> respectable 2GB of RAM.  I'd personally shell out the extra money and go for
> 1GB DIMMs and for 2-3GB, with banks open for a future upgrades if needed.
> 

Watch out on the RAM issue.  These Tyan motherboards are REALLY, and I 
mean *REALLY* picky about what RAM you put in them.  I built one with 
decent RAM (registered, ECC, but from an off-brand) and the board will 
not run.  Memtest86 SCROLLS ERRORS as fast as it can.  Linux kernel 
panics on startup.  Obviously the RAM isn't compatible.  MAKE SURE THE 
RAM YOU GET IS ON THE TYAN COMPATIBILITY LIST!

> http://www.3ware.com/
> For your hard disks, use 3Ware 7000 series RAID controllers with regular IDE
> hard drives.  You can buy several cheap 120 or 160GB drives and make RAID
> 1+0 or RAID 5 arrays for a fraction of the cost of SCSI RAID.  You get full
> hotswap and hotspare capability, and larger storage sizes than SCSI.  Yes
> SCSI can be faster, but you don't need that extra speed with LTSP.  You
> mainly need massive capacity and failover redundancy.
> 

I have little experience with 3ware cards, but I hear they work really 
well.  You'll probably want RAID5 as it gives you a combination of 
speed/size (striping) and redundancy (parity, you can lose any one 
drive, and you can have a hot spare to immediately begin rebuilding 
without having to do anything such as swap out a drive or take the 
server down to do the swapping).

You might also want to consider hot swap sleds.  This will allow you to 
swap out hard drives without shutting the box down, resulting in good 
availability.  Unfortunately, this is mostly the domain of SCSI (SCA 
connectors are SCSI), but I recall reading about sleds for IDE drives 
that had adapters that you plugged into normal IDE hard drives 
(containing a normal Molex power cable and 40pin IDE).

> DO NOT BUY Promise or Highpoint IDE RAID controllers.  They are very poorly
> supported on Linux.  Very bad idea.

They're supported, but you might as well use Linux's software RAID, 
since that's what you're doing anyway with the Promise and Hightpoint 
controllers.  I personally have a Hightpoint370 controller that I use 
all the time...as a standard single drive UDMA100 interface, but this is 
because my board has a BX chipset, so only UDMA33 off of the chipset.

> 
> Add several ethernet cards to spread out the bandwidth usage.  20 LTSP
> clients can easily eat the bandwidth of a single 100mbit ethernet port.
> 
> http://www.dlink.com/products/adapters/dfe580tx/
> This four port 100mbit ethernet card looks interesting, and appears to be
> supported by the Linux tulip driver.
> 

There are also a lot of cheap (less than $80) GIGABIT ethernet adapters 
out there that are decently supported by linux (copper of coruse). 
There was an article on slashdot a while back comparing the performance 
of them.  The problem is, a switch with a gigabit uplink ain't cheap, 
but you should be getting a really nice switch for this anyway.

Another option is the "bonding" module that linux has.  This lets you 
bond multiple interfaces together to act as one (requires a compatible 
switch, my 3com seems to work, some Ciscos are listed as compatible, but 
it will need trunking support and obviously must be managed to have the 
setup features required).  What this does is round-robins at a per frame 
level, making it look like you've got one really high bandwidth 
interface.  You could even bond multiple gigabit NICs together if you 
REALLY need a lot of bandwith (I find this unlikely for anything less 
than 20 clients).


> ----- Original Message -----
> From: "Michael Ableyev" <charon at netzero.net>
> To: <luau at videl.ics.hawaii.edu>
> Sent: Wednesday, June 12, 2002 6:14 PM
> Subject: [luau] LTSP hardware
> 
> 
> 
>>I was wondering if anyone could make a suggestion for hardware for a LTSP
.......

Hope this helps some.

--MonMotha




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