[THIN] Re: Application Availability

  • From: "Braebaum, Neil" <Neil.Braebaum@xxxxxxxxxxxxxxxxx>
  • To: <thin@xxxxxxxxxxxxx>
  • Date: Mon, 10 May 2004 09:32:07 +0100

Comments inline...

> -----Original Message-----
> From: thin-bounce@xxxxxxxxxxxxx 
> [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Shonk, Joe - Perot
> Sent: 07 May 2004 19:09
> To: thin@xxxxxxxxxxxxx
> Subject: [THIN] Re: Application Availability
> >>    Healthcare apps are very flaky.  If an application
> >> takes down a server, only that application is down.
> >Do you / anybody actually run apps that can take down servers, these 
> >days?
> It still happens...  Many of these systems are still 16 bit.

I have to say it shouldn't happen - driver code is one thing, but
applications shouldn't crash the OS.

> >> There are many hospitals
> >>    Application loads.  Single applications can have
> >> 200-300 concurrent users a piece.
> >And it's extremely unlikely you'll get a single TS / Citrix 
> server to 
> >run that 200-300 concurrent users.
> No, they are not on a single server... That's the point, 
> there are 7-10 servers allocated for one application set.  
> There is no point in bogging them down further with 
> additional applications.

Hang on a minute - then what are we arguing about?

The only reason I was making these points was regarding running an
application, or set of applications on merely one server, in response to
this that you wrote???? :-

"If the application set is isolated on it's own server then a scheduled
logoff ica-tcp is all that is needed."

See the phrase "own server" - note the singular.

> >But the flipside of it being that if an app is just 
> published / present 
> >on one server, and that server goes down, no app.
> That is why an application is installed on several servers 
> and load-balanced.  I stated that there is nothing wrong with 
> a server hosting a single application, but I never said 
> anything about only a single server.

Um, yes you did - which is the only reason I made the points I did - see

> >>    Application maintenance.  Different application sets
> >> have different maintenance schedules.
> >Agreed - I'm not against partitioning farms with applications (or 
> >application sets) in mind - merely that just having one 
> server for an 
> >app certainly restricts your options, and resiliency.
> How so?  Applications sets are across multiple servers.

That's not what you said, though.

You may have meant it, but it's not what you said - and that's the only

I think we are in aggreement, actually.

It doesn't make sense to simply run an application on one server, but it
can make sense to run a singular application across more than one

The latter, doesn't say anything logically about the former.

> >> Taking one application
> >> offline and booting off the users should not affect access to 
> >> other applications.  (Remember this is a 24/7 shop)
> >That's no reason to just publish it (or have it present) on 
> one server, 
> >though - in fact it gives you a compelling argument to *not* just 
> >publish (/ install) it on one server.
> Again, the applications sets are redundant across multiple 
> servers.  Again single application, not single server.



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