[NTLUG:Discuss] Building a new system

[Keith From]

David,
Thanks a million for your indepth insites on this subject.
You have brought up many issues that I would have never
even been aware of. 

Being fairly new to Linux, this is the kind of support that
I have learned to appriciate out of this newsgroup. 

Thank you, and everyone else here for your help in the
past, present, and future. Hopefully one day I can give
back what I have learned.

Sincerely,
Keith From


> Keith,
> 
> In order to consider what kind of machine to run as
> servers for QMail and Samba, you should perhaps
> consider several factors:
> 
> a) How many clients will be accessing the servers?
> 
> b) What is your budget?
> 
> c) What is the importance of immediate availability of
> your data?
> 
> I have seen simple Pentium boxes on Linux running very
> large websites...on the order of 150K hits per day or
> more (and yes, I know there are much bigger
> ones...these just happened to be what I personally
> observed). They were basic clone machines with 96 MB
> ram, SCSI disks, and ethernet to the machine which was
> serving as firewall and router.
> 
> The firewall/router in this case was a 486 with 32 MB
> ram and not much for a hard drive...maybe 200 MB with
> much of that unused, as I recall).
> 
> You might find you can install the same software on
> both machines, with each serving as backup for the
> other.
> 
> Another point: while performance of IDE disks is
> increasing steadily, SCSI has a definite edge for
> server use. This is primarily due to drive request
> queues. That is, the CPU sends service requests to the
> SCSI controller, which holds them in a small cache
> until they can be served. Meanwhile, the disk is able
> to remove itself from the bus until it has the
> information or until the next request is made. IDE
> drives are mostly sequential, one request at a time
> devices. Although there are some IDE controllers with
> small request queueing capability, it's a pain to be
> sure that's what you're getting.
> 
> Another way you might go for one or both of these
> servers is a server appliance, such as the Cobalt
> Cube. You can install one of these in ten or fifteen
> minutes, I understand. They are tiny boxes without
> monitors, keyboards, or other direct access devices.
> They are set up through your web browser. 
> 
> If you build the machines, there are several
> motherboard companies which make high quality boards
> and support them properly. I know there are others,
> but for the last few years I have used ASUS boards
> with great results. For my next machine, I'll probably
> do it again. I plan to use an Imation IDE floppy drive
> (Superdisk, I think they call it) that handles
> standard floppies and 120 MB floppies. I'm less
> interested in the 120 MB capability than I am by the
> fast performance for standard ones.
> 
> You won't need much on the video side, unless these
> machines will also be used as workstations. Standard
> VGA will do nicely.
> 
> I'd suggest using 128 MB of ram, unless you have a
> really big network to support. I don't know what ram
> prices are doing after the earthquake in Taiwan last
> week, but I'd imagine they are going up quite a bit.
> If you have extra money left as you are building these
> machines, extra RAM is always nice.
> 
> Ethernet cards are so cheap these days, even the top
> brands are very affordable. If you're going to use a
> 10MB card, I'd suggest anything with a DEC Tulip chip.
> Kingston made a very good one as of two years ago. DEC
> ethernet chips have the highest throughput I've ever
> seen.
> 
> If it's a 10/100 you're planning on, personally I'd
> probably still go 3Com. Both these cards are fully
> supported in Linux.
> 
> IMHO, you should also plan on very good UPS backup. I
> have a small unit by MGE that is very nice. It is an
> intelligent unit, and MGE makes a Linux driver for
> bringing the system down gracefully in the event of a
> power failure. Many of their units use Nicad
> batteries, and are about half the size of most other
> units. There is at least one vendor at the First
> Saturday flea market who sells these for a lot less
> than the stores, if you can even find one in the
> stores. Other brands may have Linux support in their
> smart units by now. I have used units by APC and Best
> Power, and have had good results with them all. 
> 
> It is very instructive to read the description on the
> MGE site about the different kinds of UPS design,
> which ever unit you choose.
> 
> The most neglected part of the machine is the power
> supply. Many people put very expensive computers
> together and use the cheapest power supplies they can
> find. If you have ever had a system crash because of a
> power glitch that didn't affect other machines on the
> same circuit, you would quickly know what I am talking
> about. At the very minimum, make sure the supply is UL
> rated and has a true ball bearing fan.
> 
> Several vendors make overheating alarms. The one I am
> most familiar with is from PC Power and Cooling. That
> one sounds an alarm if the internal temp goes above
> 110 degrees. Were you to have a fan failure, for
> example, this would warn you. There are other
> solutions if these machines will be in an area where
> people are not around to notice such an alarm.
> 
> On the subject of cooling, most quality mid tower
> cases have room to install a second fan. I'd highly
> advise doing that.
> 
> Any cheap CD that is made to directly attach to the
> IDE bus is fine. They are only used to load software
> on a server, so a high quality one is overkill (unless
> you want a CDR or CDRW to use for making backups. In
> that case, I'd go with a SCSI unit. They have fewer
> dropouts while recording. If you do that, I'd suggest
> using a different SCSI adapter for the recorder. In
> some if not in all cases, a high speed SCSI drive
> adapter can't service the drive at full speed when
> there's a slower device on the chain, which is why you
> don't put an IDE CD on the same cable as a high speed
> IDE hard drive).
> 
> If you're going to back up the server over ethernet to
> another machine, that's fine. Otherwise, you'll
> probably want a tape unit of some kind, assuming
> you're not going the CDR/CDRW route. Although they're
> more expensive, you'll likely get more service from a
> SCSI tape unit. You'll also find SCSI devices are
> easier to set up under Linux than the others. The real
> cheapies use a floppy interface, and with drives as
> big as we have today they can be excruciatingly slow
> to back up on. 
> 
> I hope this has been instructive. Sorry for the
> length, but these are areas I find most folks aren't
> very familiar with unless they're network
> administrators, engineers, or suchlike. Personally,
> I've learned most of these things the hard way.
> 
> Best of luck.
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