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

[Les Richardson <richl@mail.tfsd.sk.ca>]

Hi Andrew,

On Tue, 13 Nov 2001, Andrew Reid wrote:

> 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.

Perhaps true. But functionally from a software perspective they are.
However there are issues....bandwidth consumption between Sunray and Sun
server is horrific...each one _really_ needs dedicated 10Mbit/s to work.
There's more.....<grin>


> 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.

Actually they Sun 450's don't have the horses to do it. (even though they
could run 10,000 normal terminals...) Most services including
authentication (NIS) and home directories have been moved onto separate
Linux servers. Same thing with applications, primarily netscape and star
office. They're going on Linux app servers.

> > 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.

Netscape is a pig for ram. Also Flash _is_ a requirement in schools, since
they _just gotta_ use it to see interesting sites. Flash kills the
servers. Netscape alone perhaps would be fine, but add flash and demands
go through the roof. One errant Netscape can bring a 450 to it's knees.
Not good.

 
> > 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.

Strongly agreed.


> 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.

The new 160MB/sec interfaces can certainly push a lot of drives before
you're scsi bus bound. Real world performance for a drive probably doesn't
exceed 5-10MB given a lot of seeks, etc. Also, we don't put that many in
for most servers. Just build more servers...

The Sun servers have 10 - 10k scsi drives but those boys have I/O to burn.
In those boxes it is used to give more "virtual ram" to enable them to run
the Sunrays. A poor engineering match in my view. (I don't really like the
Sunray at all...they're pretty, but a real X terminal would be a much
better solution IMHO.)

> 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).

Windows and "Up to Date" must be an oxymoron... No, we just ghost them and
then lock them down using Deep Freeze. Very little required in the way of
management, other than periodically updating the image, and reghosting. We
try to get them as close to being a terminal as we can. 


> 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).

Yes, NIS is used since the Sun boxes came installed that way. LDAP is
certainly the way to go, however, it all takes development time to sort
all the issues, etc.

Owen Odonovan is the brain at the local school division if anyone has any
questions. Owen's email is: osod@bsd.sk.ca


Les Richardson
H. Hardcastle School
Edam, Sk.