[THIN] Re: Application Availability

  • From: "Braebaum, Neil" <Neil.Braebaum@xxxxxxxxxxxxxxxxx>
  • To: <thin@xxxxxxxxxxxxx>
  • Date: Fri, 7 May 2004 16:56:16 +0100

Comments inline...

> -----Original Message-----
> From: thin-bounce@xxxxxxxxxxxxx 
> [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Shonk, Joe - Perot
> Sent: 07 May 2004 16:32
> To: thin@xxxxxxxxxxxxx
> Subject: [THIN] Re: Application Availability
> For several reasons:
>       A dept/project buy a set of servers to deploy a single 
> application

Numerous servers, single application - sounds good! ;-)

>       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

> It does 
> not affect other critical systems
>       Application limitations only allow 1 instance of 
> whatever (database, group etc).

Then it's unlikely it would run in a PC environment, then (ie running on
numerous PCs).

The problem with an app just on one server, is that it's dependent on
that *one* server.

> 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.

>       Security/HIPAA requirements.  Finance doesn't need 
> access to clinical apps and doctors do not need access 
> finance applications.

What's that got to do with an app running on just one server, though?

That's more to do with their environment providing access to the
application - not whether it's just published (or present for that
matter) on one particular server.

>       Compatibility issues with multiple apps on a server 
> (again see the flaky line above)

True - that can happen.

There's things that can be used, these days, to mitigate that.

But the flipside of it being that if an app is just published / present
on one server, and that server goes down, no app.

>       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.

> 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.

>       Oh, and I forgot... The number #1 reason:   Politics

Political and managerial people do not need to know that level of
detail, though (which servers, publish which apps) - that's a technical

> Never said it was perfect,
> Joe
> -----Original Message-----
> From: Braebaum, Neil [mailto:Neil.Braebaum@xxxxxxxxxxxxxxxxx] 
> Sent: Friday, May 07, 2004 1:26 AM
> To: thin@xxxxxxxxxxxxx
> Subject: [THIN] Re: Application Availability
> Comments inline...
> > -----Original Message-----
> > From: thin-bounce@xxxxxxxxxxxxx
> > [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Shonk, Joe - Perot
> > Sent: 06 May 2004 17:36
> > To: thin@xxxxxxxxxxxxx
> > Subject: [THIN] Re: Application Availability
> > 
> > Why not use a custom load evaluator for the custom app? Then
> > script a logoff to force the users out of the application?  
> > If the application set is isolated on it's own server then a 
> > scheduled logoff ica-tcp is all that is needed.
> Why restrict yourself to only having an application on one 
> server - this sort of thing (logging off user sessions, based 
> on the published app they are running) then means you only 
> take an application down, and can balance it, and have it 
> benefit from the redundancy of being able to run over more 
> than one server.

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