Re: [seul-edu] How big a server?

[Andrew Reid <andrew.reid@plug.cx>]

On Mon, Nov 12, 2001 at 11:00:00PM -0600, Les Richardson wrote:

> A friend of mine is running a _very_ large Sunray appliances (X Terminal
> Wannabees). Using large Sun 450's for application service bogged down
> since the Sunray software (which implements the rest of the X Terminal
> emulation) also runs on the Sun server. The solution is to move
> application service and login/homefolders onto separate boxes. 

Interesting comment -- "Sunray appliances (X Terminal
Wannabees)". They're not exactly X Terminals. There's a lot that's
done differently that makes the SunRay fairly different.

It seems to be the case when rolling out large quantities of SunRays
that you end up with more server power than you thought you
needed. This is generally because the analysis work at the school
didn't function correctly, giving the people at Sun the wrong idea.

> If considering application services for X display servers running on NT
> boxes (although Dual Boot would be nice and entire drive could be
> ghosted...(this is the setup we run)) you will have to consider the memory
> requirements for a running app per user. If we assume 100Mb per user for
> example, then 50 users will need about 5GB of Ram. Typically one can stuff
> about 3-4 GB per server (even a Sun...4GB per processor). So perhaps build
> a couple of server to start.

... but remember that not all your users are going to suck 100MB all
the time. If they're just running Nutscrape for example, you could
chop some of that figure off.

> I would suggest, for starters, build a nice Dual Processor System with 4GB
> of Ram using either a Systemworks board (about 10 of these running
> locally) or one of the Asus CUV4 thingy's (Dual Processor also).
> 
> Both have onboard scsi with LVD support. I would put 4+ 9GB drives into
> those things (more spindles = better so don't buy big drives). Intel
> NIC's. Good case, IDE CD, etc. 

If you're able to put these drives into a RAID-5 array, you'll notice
significant performance increases. Bear in mind though, the SCSI
controller is going to have a limit to the amount of data that it can
move per-second. So, if you put 4 80MB/second drives on the one
interface, the maximum (theoretical) amount of data per-second that
any one drive could move (whilst other drives are also transferring
data at their maximum speed), is 20MB/second.

To complicate it further, the drives themselves are probably only
going to be able to move about 20MB/second.

> These app servers are all clones and use rsync to mirror off a master.
> (i.e. easy to maintain and add apps, etc.)

Have you got an rsync-based system for keeping your windows boxes
up-to-date too? I've got that kind of thing happening under
Linux/FreeBSD, but not under Windows (using rsync).

>  I wouldn't be that keen to build a "mother of all servers". Single point
> of failure, although simpler management of course.

It could be simplified however. Through the use of things like LDAP or 
(god forbid) NIS, you're able to centralise things a fair bit. LDAP is 
really good at this kind of thing, particularly if you have to
replicate a lot of configuration information across multiple servers
(ie, for load-balancing purposes).

   - andrew

-- 
Andrew J. Reid                    "Catapultam habeo. Nisi pecuniam omnem  
andrew.reid@plug.cx               mihi dabis, ad caput tuum saxum immane 
+61 401 946 813                   mittam"