It all started when the place I used to work at threw out a pile of old PC base units along with a big box of (unopened) Windows 98 disks !
I got as many PC's as I could carry for £5 each (OK, so they were Pentium MMX 233's with 16Mb of SIMM, a 3c509 (ISA) network card - but they all had CD drives and some had even been 'upgraded' to 500 Mb hard disk !). I also deprived the dustmen of the Win98 CD's.
What to do with this windfall ? - well I was already running seti on my 'home' PC and had heard of the DC Farm systems being put together in the USA so I decided to have a go too !
My first system was simply 8 PC's wired together with a low cost
(10mbs) Hub - they all had hard disks but only one had keyboard/mouse/monitor
- and this acted as the 'central store' = it had a dial-up Modem connection
to the Internet and every night I would
(manually) upload the 1 to 5 (depending on crashes etc) completed units and
download some new ones. In those days it took about 25-30 Hrs to complete
each unit :-)
This remained the same for about 6 months - then I discovered eBay !
The rest, as they say, is history.
A dozen or so old motherboards and an 18 port Hub later and I was building my very first 'Seti-Wall'
The shelves where still being used for other things in those days, and I since I only had one 18 port Hub I was somewhat limited :-) - but I soon realized that fitting the new motherboards with a hard disk was going to be both expensive and noisy !
So I spent the next 6 months getting the system to boot Windows 98 from a network 'share' - without the benefit of Microsoft's help (in fact their software seems to go out of it's way to prevent any such thing) and without using Windows Terminal Server (and paying more money to Microsoft).
Now I have two 8 port & one 32 port switch (and not all the port are filled - but the wall is :-) - so those same old MMX 233 boxes are still doing service (OK, now they have AMD K6-III's inside, but it's still the same old box).
So how did I do it?
You can either read the faq below or dive straight into the How-To!
FAQ
(everyone should have a FAQ)
1) Microsoft says Windows 98 can't (won't :-) ) run from a RAM disk ?
3) What about the Windows boot Registry setup sequence ?
4) How can you run networking in Windows with the 16 bit drivers loaded by DOS ?
5) But running from RAM disk means nothing gets 'saved' after a power-outage !
6) Why use a Switch (and not a Hub) ?
7) What's the best Processor for seti ?
8) What did it cost to build ?
10) What's it all cost to run ?
11) What does the 'other half' think about it all ?
A) A typical 'node' with motherboard (on-board video), network card, (small) PSU and boot floppy.
C) 'Seti Wall' - the View from the door
D) 'Seti Wall' - the View from the 'command console' !
Answers
1) Microsoft says Windows 98 can't (won't :-) ) run from
a RAM disk ?
So why can't Windows detect that it's running from a RAM disk ?
Windows doesn't know it's running from a RAM disk. It thinks it's
running from a Compacted hard disk.
At floppy boot time, both the RAM disk driver and the (16 bit) Compaction driver
load well before Windows even thinks about getting started. So all attempts
by Windows to access the 'physical' c:\ drive have to go via the Compaction
driver - which in turn goes via the RAM disk driver !
"But wait a moment - booting into DOS and booting into Windows involve totally different processes (DOS is 16 bit, Windows 32 bit) - surly there's no way DOS can suddenly switch over to Windows ?"
Although Windows is a 32 bit o/s it is running 'on top of' DOS - and although the boot processes are indeed different, 'win.com' does the trick of 'launching' Windows from DOS. This, by the way, is not true for NT or 2000 - these are 32 bit o/s with non-DOS boot sequences (and there is no such thing as 'NT.com').
3) What about the Windows boot Registry setup sequence
?
"Now that sounds OK, but I know for a fact that 'windows DOS' is not the
same as 'DOS DOS' - amongst other things, Windows 98 'DOS' mode prepares for
later 32 bit running by examining the Motherboard BIOS and hardware during the
boot-up and creating values for the Registry to pick up later. So why doesn't
the Register initialization process get 'upset' and cause Windows launch to
fail ?"
No idea - maybe because the 'node image' was created on the 'node hardware' itself and since good old Windows 'Plug & Play' is just about able to 'cope' with being moved to a different motherboard, when no values are found, it just drops back to the 'last used' set (which, of course, are OK since it's actually still on the same hardware) ??
4) How can you run networking in Windows with the 16 bit
drivers loaded by DOS ?
The 16bit DOS network drivers are unloaded from RAM when the 'net stop' command
is issued. So when Windows launches, no network drivers are present (and IFSHLP
will have 'reserved' the crucial low RAM for Windows to use).
5) But running from RAM disk means nothing gets 'saved'
after a power-outage !
True - this is why you have to install seti on the mapped 'share' drive (so
that your 'work in progress' is saved to the 'Server' hard disk on the node
parent PC).
6) Why use a Switch (and not a Hub) ?
Because I got the 10/100 Switch cheap on eBay at the time I was moving from
10mbs to 100.
With a 100Mbs network, you aren't going to see much difference between a switch
& a hub
(a hub might even be faster since there is going to be some overhead as the
switch
decides 'where does this packet need to go ?').
NB. The only reason for going 100mbs was to speed up the boot process (moving a 30Mb 'image' across the network is reduced to a few seconds).
7) What's the best Processor for seti ?
1) Quick answer = whatever is cheap on eBay :-)
2) OK, Pentium III's are best, AMD K6-II are the worst (they have crap Floating
Point)
Today's AMD's are much better (but also need fancy DDR RAM and such like ..)
- so
the Pentium range (PII, III & Celeron) still wins.
3) As of today (November 2002), the best 'bang for the buck' is, without doubt,
the
1GHz Celeron (you can get them at 30 to 40 quid) - their 100MHz FSB also means
a
cheap motherboard.
4) Xeon used to be "The God of Seti 'crunching' " - but with the current
3.03 Client
the big Xeon L2 cache no longer makes much difference and they are no longer
worth
the extra cost ...
8) What did it cost to build ?
Very approx ...
Motherboard 20 (average)
128Mb RAM 12
PIII 450/Cel 533 28 (average)
Heatsink & fan 5 (must have good quality fans - they make less noise !)
PSU 5
3c905c 3 (approx - I got 12 for 30 quid)
Floppy drive (new) 7
FD, net & PSU cable 3 (£1 ea from the Computer Fairs)
98 Licence 0 (Computer Fairs will have Windows98 at anything from 20 to 50)
==
83
Add in 'part costs' (Switch, Server, KB/Mouse/Monitor/KVM),
a few 'premium' parts
(a couple of £35 1GHz Celeron's) and 'wastage' (blown motherboards) and
you get a
'ball park' of ... 'less than £100 per node'.
9) What about power ?
Use PSU's that are as small as possible - the more unused watts you have the
less efficient the PSU is at producing the watts you are using (and hence the
more heat) - I have mainly used 135watt units picked up by the 'box load' at
Computer Fairs (no-one wants them & you can pay less than £5 each
if you buy a dozen at a time ('Tell you what, how about 50 quid for the whole
box ?' ).
WARNING - make sure these are NOT 'system pulls' - check VERY
carefully that they are
'brand new' / 'old stock' / 'un-used' ... PSU's are usually the first thing
to go wrong
with any PC - get some 'used' PSU's and you WILL end up 'frying' a motherboard/CPU
or two
whilst trying to work out which are the 'duffs' (I know, I did :-) ).
NB - for those of you with fancy 'Earth Leakage Detector' house
Mains power circuits (ELCB's, RCD's etc) - playing with all those switch mode
PSU's you are going to 'trip' your house power about once a month - real pain
!
I now run mine on it's own protected 'spur' before the main trip - when they
trip, they only take out the 'seti wall'.
10) What's it all cost to run ?
1) I don't like to think about it :-)
2) I save money on the heating because my seti-wall keeps the house warm ...
11) What does the 'other half' think about it all ?
1) I don't know - I never see her during the week and at weekends we are far
too busy :-)
2) But the cat loves it (all those nice warm boxes to lie on).
12) Anything else ?
Get it insured - also get Smoke Detectors.
A) A typical 'node' with motherboard (on-board video), network card, (small) PSU and boot floppy.
B) OK, not all nodes are diskless ! The big box to the left is then 'server' and note 4 way KVM switch which saves moving cable all the time
C) 'Seti Wall' - the View from the door
D) 'Seti Wall' - the View from the 'command console' !
