hagrp -switch

[Aerosmith1]

 Hi ,

 VCS version is 3.5 and OS is solaris 9

 just a basic question, I am going to do following command on one of
 the cluster nodes to switch application service group to other node.
 Application SG includes resources like SAN disks, http, tomcat, oracle
 listener/DB

 # hagrp -switch service_group -to system

 I am wondering what happens to the users who are logged into the
 web-site already and writing to a forum may be..: do they have to
 re-login? and do they lose all data while writing a post in
 application based discussion forum?

 Please let me know,

 Thanks

[Roger_Zimmerman · Accepted solution]

Hi,

when web applications are switched the user normally have to relogin to the web server. This is because of the kind how a web application identifies an user. Normally there is a session cookie what is checked in any communication phase.

When you switch a web server the session cookies from the "old" node normally will be rejected, all sessions have to be restartet (relogin). And then a second question is if the date from the web formular (posting, blog etc.) can be "recycled" in this new session. Sometimes you have a comlete loss of actual work.

The story is different, if you have before the web server a "frontend server" what is holding the session cookie. Then the "frontend server" is (normally) able to reconnect the session to the web server.

Architecture:

web server --> web browser

there it is most likely to loose some work because of restarting the sessions

Architecture:

web server --> web frontend --> web browser

there it is poosible to suvive the switch of the web server (but not the switch of frontend :) )

So, while this is not primarily a cluster problem, you should talk to you web guys. Or even try to restart the web server, it`s the same procedure. If you have then a reconnect then you have also this reconnect when you switch your service group.

Regards 

Roger

[Aerosmith1]

Thanks for this information, Roger

Great Day !