[f-nsp] multiple service failover

[manolo]

David,
  
   You can track the port health of any one of the two application ports
and declare that vip as unhealthy this failing it. The pdf docs are out
there on how to track that.



Manolo

Manu Chao wrote:
> i am sure a vendor like f5 will help you to overcome your applications
> limitations
> On Tue, Jul 14, 2009 at 4:26 PM, David Miller <syslog at d.sparks.net
> <mailto:syslog at d.sparks.net>> wrote:
>
>     Hi All;
>
>     I've got a situation that I'm not sure of the best way to handle.
>
>     I have a pair of servers that are able to run the same
>     application.  Caching issues make it weird though.  The
>     application writes to the database when updates come in, and (of
>     course) updates its own internal cache.  The servers don't update
>     each other, however, nor do they get updates from the database any
>     time other than at startup.  "startup" in this case is defined as
>     the first query that hits tomcat.
>
>     What this means is that I want to run off S1 as long as its
>     running.  And if S1 becomes unavailable I want to run off S2 until
>     I come back and fix things. lb-pri-servers takes care of that part.
>
>     Here's the complicated part.  The servers accept SSL as well for
>     user authentication.  I need http and ssl to fail to S2 as a pair
>     - both or neither.  We recently had application response issues
>     where S1 was very slow to respond, and http failed over but ssl
>     did not.  This broke the customers ability to authenticate.  We're
>     terminating ssl on the ServerIron 4G's and talking plaintext on
>     port 443 to the server.  Apache is listening on 80 and 443
>     expecting plaintext.
>
>     We've played with boolean health checks, but I haven't implemented
>     them.  I'm concerned about separate health checks because nothing
>     different is being tested.  It seems like a race condition would
>     still exist where http would fail over, but a second later the ssl
>     check would pass.  What we need is for a single failed health
>     check to down the server and fail all services over to the backup.
>
>     If it makes things easier, we can just skip the ssl test.  A
>     single test for http is adequate for making sure apache is
>     responding on the server.
>
>
>     Suggestions very welcome.
>
>     --- David
>
>
>
>
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