[Linux-cluster] High Availability options

[Stephen Kirkpatrick]

Hello all,

I am new to this list and am seeking advice from those of you who have 
experience with high availability on RHEL.  I have been researching this 
through Google and have observed several options, but don't know what 
would be most appropriate for our deployment.

Here is our deployment:

Application
    - Users run the application through an ssh login session.
    - The application runs on the server and the display is rendered
      on the end user's desktop.  (We are not using X here, but this
      is conceptually the same as running remote X apps).
    - The application is backed by a database (IBM Informix) on the
      same machine
    - Using Red Hat EL 3 (ES)

Hardware
    - IBM xSeries server (I noticed clustering support for some of
      IBM's ServeRAID controllers in The High-Availability Linux
      Project, in case anyone is using this feature)
      - these servers have dual onboard NICs
    - SCSI disks - no SAN will be used

Goals
    - Minimal downtime (preferably zero downtime) in the event of a
      hardware failure

My main concern with providing HA for our environment is to not
interrupt our SSH login sessions.  While there are other network
services running, such as Apache, these services could tolerate a
short interruption in the event of a failover.

Does anyone have opinions on offerings such as the High-Availability
Linux Project, Red Hat Cluster Suite, Linux Virtual Server, just to
mention a few.  I am not opposed to a commercial offering, as long
as it isn't prohibitively expensive.  I don't want to spend more on
HA software than the investment in hardware.

TIA,

Stephen Kirkpatrick