On Fri, Sep 30, 2011 at 10:06:51AM +0200, Gerald Vogt wrote: > Hi! > > I am running a cluster with 3 nodes. These nodes provide dns service. > The purpose of the cluster is to have our two dns service ip addresses > online at all times. I use IPaddr2 and that part works. > > Now I try to extend our setup to check the dns service itself. So far, > if a dns server on any node stops or hangs the cluster won't notice. > Thus, I wrote a custom ocf script to check whether the dns service on > a node is operational (i.e. if the dns server is listening on the ip > address and whether it responds to a dns request). > > All cluster nodes are slave dns servers, therefore the dns server > process is running at all times to get zone transfers from the dns > master. > > Obviously, the dns service resource must be colocated with the IP > address resource. However, as the dns server is running at all times, > the dns service resource must be started or stopped after the ip > address. This leads me to something like this: > > primitive ns1-ip ocf:heartbeat:IPaddr2 ... > primitive ns1-dns ocf:custom:dns op monitor interval="30s" > > colocation dns-ip1 inf: ns1-dns ns1-ip > order ns1-ip-dns inf: ns1-ip ns1-dns symmetrical=false
maybe, if this is what you mean, add: order ns1-ip-dns inf: ns1-ip:stop ns1-dns:stop symmetrical=false > > Problem 1: it seems as if the order constraint does not wait for an > operation on the first resource to finish before it starts the > operation on the second. When I migrate an IP address to another node > the stop operation on ns1-dns will fail because the ip address is > still active on the network interface. I have worked around this by > checking for the IP address on the interface in the stop part of my > dns script and sleeping 5 seconds if it is still there before checking > again and continuing. > > Shouldn't the stop on ns1-ip first finish before the node initiates > the stop on ns1-dns? > > Problem 2: if the dns service fails, e.g. hangs, the monitor operation > fails. Thus, the cluster wants to migrate the ip address and service > to another node. However, it first initiates a stop on ns1-dns and > then on ns1-ip. > > What I need is ns1-ip to stop before ns1-dns. But this seems > impossible to configure. The order constraint only says what operation > is executed on ns1-dns depending on the status of ns1-ip. It says what > happens after something. It cannot say what happens before something. > Is that correct? Or am I missing a configuration option? > > Thanks, > > Gerald -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com _______________________________________________ Pacemaker mailing list: Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
