On Thu, Dec 29, 2011 at 5:06 PM, Digimer <li...@alteeve.com> wrote: > On 12/29/2011 04:49 PM, Achint Mehta wrote: > > Hi All, > > > > I am using RHCS in RHEL 6.2. > > > > I am trying to perform a failover for a node in the cluster. > > All the services have fail-over configured on them with recovery method > > set to relocate. > > When the node foes down the services are not relocated to to another > nodes. > > > > Though the node failure is detected by rgmanager: > > ------ > > Dec 29 16:20:57 rgmanager State change: pcs_linuxha_1 DOWN > > Dec 29 16:28:25 rgmanager Status Child Max set to 7 > > ------ > > and fenced has the following logs: > > ------ > > Dec 29 16:21:04 fenced fencing node pcs_linuxha_1 > > Dec 29 16:21:04 fenced fence pcs_linuxha_1 dev 0.0 agent none result: > > error no method > > Dec 29 16:21:04 fenced fence pcs_linuxha_1 failed > > ------ > > > > 1. Do I require fencing to be enabled to make node failover work > > 2. If yes, what kind of failover device should I add. (all the nodes are > > simple servers.) > > > > > > Thanks! > > Achint > > Yes, you absolutely needs fencing. > > As soon as a node is lost, fenced informs dlm which then stops providing > locks. Only when the fence succeeds is dlm informed and will again issue > locks. In turn, rgmanager uses dlm, so with dlm not providing locks, > rgmanager can't recover services. > > See this for a more specific explanation; > > > https://alteeve.com/w/2-Node_Red_Hat_KVM_Cluster_Tutorial#Concept.3B_Fencing > > -- > Digimer > E-Mail: digi...@alteeve.com > Freenode handle: digimer > Papers and Projects: http://alteeve.com > Node Assassin: http://nodeassassin.org > "omg my singularity battery is dead again. > stupid hawking radiation." - epitron >
Thanks for the explanation. It appears that until fence daemon performs the fencing activity the recovery will not be made. So I would have to setup fencing. 1. I am not sure what kind of fencing device to add for simple servers. 2. Is this fencing device supposed to be a dedicated machine outside of the cluster. 3. Also, would fencing be successful if the node to be fenced is not reachable on the network. --Achint
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