As I keep saying; If corosync dies, the cluster stack on the node fails. So if corosync is dead, that node will not do anything; It will not fence, it will not restart services, nothing. If you somehow lose corosync on all nodes at the same time, then your cluster is dead.
Clusters protect against single points of failure. Rarely can multiple simultaneous failures be protected against. On 12/03/2012 07:07 AM, Hermes Flying wrote: > I see, I will look into this. > There is one thing I am confused about. > If I have Node-A/Node-B/Node-C and let's say Node-A has the VIP. > What happens if corosync fails in all nodes? Will all 3 try to kill > eachother? > > > ------------------------------------------------------------------------ > *From:* Digimer <li...@alteeve.ca> > *To:* Hermes Flying <flyingher...@yahoo.com> > *Cc:* General Linux-HA mailing list <linux-ha@lists.linux-ha.org> > *Sent:* Monday, December 3, 2012 1:20 PM > *Subject:* Re: [Linux-HA] Corosync on cluster with 3+ nodes > > Most Fujitsu servers work with fence_ipmilan. I suspect the same is true > with the IBM servers. Ask the hardware people if they have out-of-band > management on the servers (which is the generic/marketing way of saying > IPMI or the like). > > On 12/03/2012 05:00 AM, Hermes Flying wrote: >> Some are IBM servers mentioning VMK (optional) and others are Fujitsu >> mentioning iRMC. >> Not sure what can I do in the IBM case >> >> >> ------------------------------------------------------------------------ >> *From:* Digimer <li...@alteeve.ca <mailto:li...@alteeve.ca>> >> *To:* Hermes Flying <flyingher...@yahoo.com > <mailto:flyingher...@yahoo.com>> >> *Cc:* General Linux-HA mailing list <linux-ha@lists.linux-ha.org > <mailto:linux-ha@lists.linux-ha.org>> >> *Sent:* Sunday, December 2, 2012 10:36 PM >> *Subject:* Re: [Linux-HA] Corosync on cluster with 3+ nodes >> >> I don't know anything about your setup or office situation, so I can't >> speak to your specific issues. >> >> What I can say is that almost all actual servers have remote management; >> Fujitsu servers have IPMI, HP servers have iLO, Dell servers have DRAC, >> IBM servers have RSA and so on. Most generic servers have at least basic >> IPMI. So it's very likely that you will already have what you need to >> implement fencing. If you don't, then something like the APC AP7900 is >> usually about $500 canadian and will work as a fence device. I don't >> know what country you are in, so I can't speak more on availability, >> applicability or cost. >> >> You might seriously want to consider hiring someone to help you with >> this setup. Clustering is not a straight-forward topic. The cost to hire >> a consultant might save you enough time and headache that it's cheaper >> in the end than trying to do it yourself. >> >> On 12/02/2012 03:31 PM, Hermes Flying wrote: >>> I am an application developer and so far I didn't care about HW specs >>> (not my responsibility). >>> Now it seems I must care and so since I am not sure what HW is being >>> recommended for servers I will verify tomorrow and let you know. >>> My concern is that by going to pacemaker (although seems to be exactly >>> what I need) is that we would need to request for new HW on migrate to >>> new deployment. I don't even know if these devices are expensive. >>> Did you ever had an issue with this? If I have problem with this, should >>> I be looking into different solution? Any suggestion for alternative? >>> >>> >>> ------------------------------------------------------------------------ >>> *From:* Digimer <li...@alteeve.ca <mailto:li...@alteeve.ca> > <mailto:li...@alteeve.ca <mailto:li...@alteeve.ca>>> >>> *To:* Hermes Flying <flyingher...@yahoo.com > <mailto:flyingher...@yahoo.com> >> <mailto:flyingher...@yahoo.com <mailto:flyingher...@yahoo.com>>> >>> *Cc:* General Linux-HA mailing list <linux-ha@lists.linux-ha.org > <mailto:linux-ha@lists.linux-ha.org> >> <mailto:linux-ha@lists.linux-ha.org <mailto:linux-ha@lists.linux-ha.org>>> >>> *Sent:* Sunday, December 2, 2012 10:19 PM >>> *Subject:* Re: [Linux-HA] Corosync on cluster with 3+ nodes >>> >>> It must be an external device. If, for example, the kernel crashes hard, >>> or if you get a spinlock, the system may not respond to anything or a >>> service may never stop, blocking a reboot. You can not trust that the >>> system is accessible or functioning in any way. >>> >>> Fencing *must* be an external device. Period. >>> >>> What kind of servers do you have? >>> >>> On 12/02/2012 03:15 PM, Hermes Flying wrote: >>>> If I have a requirement not to include external HW, is there any other >>>> way? I mean, I am not -by far- a linux expert, but how come it doesn't >>>> do a restart or halt? >>>> >>>> >>>> ------------------------------------------------------------------------ >>>> *From:* Digimer <li...@alteeve.ca <mailto:li...@alteeve.ca> > <mailto:li...@alteeve.ca <mailto:li...@alteeve.ca>> >> <mailto:li...@alteeve.ca <mailto:li...@alteeve.ca> > <mailto:li...@alteeve.ca <mailto:li...@alteeve.ca>>>> >>>> *To:* Hermes Flying <flyingher...@yahoo.com > <mailto:flyingher...@yahoo.com> >> <mailto:flyingher...@yahoo.com <mailto:flyingher...@yahoo.com>> >>> <mailto:flyingher...@yahoo.com <mailto:flyingher...@yahoo.com> > <mailto:flyingher...@yahoo.com <mailto:flyingher...@yahoo.com>>>> >>>> *Cc:* General Linux-HA mailing list <linux-ha@lists.linux-ha.org > <mailto:linux-ha@lists.linux-ha.org> >> <mailto:linux-ha@lists.linux-ha.org <mailto:linux-ha@lists.linux-ha.org>> >>> <mailto:linux-ha@lists.linux-ha.org > <mailto:linux-ha@lists.linux-ha.org> <mailto:linux-ha@lists.linux-ha.org > <mailto:linux-ha@lists.linux-ha.org>>>> >>>> *Sent:* Sunday, December 2, 2012 10:01 PM >>>> *Subject:* Re: [Linux-HA] Corosync on cluster with 3+ nodes >>>> >>>> On 12/02/2012 02:56 PM, Hermes Flying wrote: >>>>> Clear! In order to do fence and crash a node, is there a specific HW >>>>> requirement to do this? >>>> >>>> Yes, there must be external hardware (out-of-band management counts as >>>> "external", despite physically being on the server's mainboard). The >>>> most common fence device is IPMI, iLO, RSA, iDRAC and the like. >>>> Alternatives are switched PDUs, like APC's AP7900. >>>> >>>> -- >>>> Digimer >>>> Papers and Projects: https://alteeve.ca/w/ >>>> What if the cure for cancer is trapped in the mind of a person without >>>> access to education? >>>> >>>> >>> >>> >>> -- >>> Digimer >>> Papers and Projects: https://alteeve.ca/w/ >>> What if the cure for cancer is trapped in the mind of a person without >>> access to education? >>> >>> >> >> >> -- >> Digimer >> Papers and Projects: https://alteeve.ca/w/ >> What if the cure for cancer is trapped in the mind of a person without >> access to education? >> >> > > > -- > Digimer > Papers and Projects: https://alteeve.ca/w/ > What if the cure for cancer is trapped in the mind of a person without > access to education? > > -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education? _______________________________________________ Linux-HA mailing list Linux-HA@lists.linux-ha.org http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
