I think Lea means: For cluster takeover to work seamlessly, your application has to keep session data in some common location between the servers. If that's the case, then when the shutdown of the second server commences, it takes itself out of the load balancer queue, completes whatever transactions are in flight at that moment on that node, signals the other node that it's now in charge, and then takes a swan dive into oblivion. The other node takes the session state data from the shared location, and picks up where the original node left off. Works well for applications that are aware of how to play nicely.
If you go all the way to OpenSSI, then a node shutdown triggers process migration to nodes other than the one going down, and the system continues operation without the application even noticing. It takes some planning to get clustered applications to work properly, but once that's done, it's pretty slick. RTFineM for 'cluster' for more interesting details. Once you have the cluster properly configured for takeover, then you use VMUTIL or S5INIT to issue the SIGNAL SHUTDOWN to each node in turn, back it up, then XAUTOLOG it so that it re-enters the cluster and all is well. David Boyes Sine Nomine Associates > -----Original Message----- > From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of John > Summerfied > Sent: Thursday, July 27, 2006 7:46 PM > To: [email protected] > Subject: Re: Bad Linux backups > > Stahr, Lea wrote: > > A piece of cake! Use VMUTIL on VM to do the shutdowns and startups and > > have the backups scheduled appropriately. Or get the CONTROL-M agent and > > have that do it all from ZOS. > <snip> > > I don't understand how that addresses my concern. > > > > Stahr, Lea wrote: > > > >>With clustering, you shut down one image and do an OFFLINE backup > > > > while > > > >>the application runs on the second image. Then bring up the primary > >>image and shutdown the secondary system for backup. > >> > > > > > > which sounds every bit as tricky to me as getting good backups from a > > live Linux system. > > > > I'm negotiating purchase of a PC with your online retail shop and you > > take down the box I'm talking to while I'm negotiating PC options such > > as RAM, CPU, disk.... > > > > > > > > -- > > > > > -- > > Cheers > John > > -- spambait > [EMAIL PROTECTED] [EMAIL PROTECTED] > Tourist pics http://portgeographe.environmentaldisasters.cds.merseine.nu/ > > do not reply off-list > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
