[LON-CAPA-admin] RE: access server requirements

[Mark Lucas]

On Thu, 3 Oct 2002, Guy Albertelli II wrote:

> Hi Martin,
> 
> > On Thu, Oct 03, 2002 at 01:11:44PM -0400, Ron Fox wrote:
> > > 
> 
> > I am also wondering whether we should invest in high-availability
> > servers from one of the "big" companies (IBM, Dell, etc.) or whether
> > we can get away with a "noname" product for almost half the price.
> > Is it correct for LON-CAPA that if one of the access server crashes
> > the other one and the library server will take over the load seamlessly
> > without noticeble effect for the users? 
> 
> Only the users currently working on the crashed machine would notice.
> And yes properly configured the others should just take over.

We use a round-robin list on the dns. Is there a way to get it to bypass a 
machine if it has disappeared temporarily? (I realize you can modify the 
DNS configuration if it is permanent).
With two access servers, if oucapa7 craps out, every other hit will claim 
it can't find the machine.


As for cpu on the library server, I get the feeling it needs to be fairly  
beefy to keep the instructors happy. A number of processes take a lot of 
time when the class size gets up into the hundreds. I'm not exactly sure 
how much I/O is being done, but I gather that you'd prefer for the 
instructor to do it on the local (library server) machine with the 
records.


One question on memory - I've been noticing that the apache children get 
big (27+MB) and that my machines with 380MB of RAM don't seem to swap out 
apache children or lonc/lond processes. Is there an explanation as to why 
not? I thought we were supposed to make ungodly large swap spaces just for 
that contingency. How ludicrous is the 4MB number posted earlier? (specs 
from a couple years ago suggested 1MB for the access server).

						Mark



----------------------------------------------------------------------------
Mark Lucas					email: lucasm at ohiou.edu
252D Clippinger Lab  				phone: (740)597-2984
Department of Physics and Astronomy             fax:   (740)593-0433
Ohio University
Athens, OH 45701