Re: HDR+Connection Manager in intermittent network scenario

I agree with Paul, especially if you have the CM managing failover, but even if not it's a very good idea! Art Art S. Kagel Advanced DataTools (www.advancedatatools.com) IIUG Board of Directors (art@iiug.org) Blog: http://informix-myview.blogspot.com/ Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Advanced DataTools, the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Wed, Dec 8, 2010 at 2:46 PM, <mosserp@wellsfargo.com> wrote: > > On 12/03/2010 07:46 PM, Nate Woodward wrote: > > > I'm trying to acheive high availability without data loss. I have an > > HDR > > > pair configured with a connection manager on each box for redundancy. > > > Clients are pointed at an sqlhosts group with the connection managers > > in > > > them, and the connection managers are configured to redirect the > > clients > > > to the current primary server in the pair. The connection managers > > are > > > also configured for failover, with FOC = HDR,10, so that the > > secondary > > > takes over the primary's job if it fails. > > > > > > Now, I'm worried about this scenario: > > > - primary gets disconnected from network > > > - secondary is brought to primary mode > > > - primary regains network connectivity > > > - two primary's are on the network -- what now? > > > > > > I'm considering writing an ALARMPROGRAM script to bring down the > > primary > > > if it loses network connectivity, so that HDR can be re-established > > with > > > the old secondary as the new primary. Is there a better way to do > > what > > > I'm trying to accomplish? > > > > > <snipped> > > It is mainly because of dangerous situations like this (dual primaries) > that I maintain that there should be a *third* server to monitor both the > primary and secondary. Besides monitoring, that third server should also be > the one to execute the switchover of the primary duties to the secondary > server (when the old primary becomes unresponsive), and should also be the > one to re-direct the client traffic to the new primary db server. This is > the very successful model that we put in place here in 2004 for a highly > critical HDR pair -- obviously, this was *before* MACH 11 and Connection > Manager. (for more info, see my presentation from the 2006 NA IIUG/IDUG > Conference, available in the member area of iiug.org) > > My recommendation would be to put the Connection Manager on a small *third* > server, ideally situated very close network-wise to the majority of your > client connections. The redundant CM should ideally be on a fourth server, > but also located close by client servers. The main point here, of course, > is to *NOT* have your CM on the same server as your DBMS. > > HTH, > Paul Mosser > _______________________________________________ > Informix-list mailing list > Informix-list@iiug.org > http://www.iiug.org/mailman/listinfo/informix-list >