Hi For this question: Is it possible to control even for multiple instances of apache? like i have node 1 running 2 instances of apache and another node running 1 instance in apache. If my apache server goes down will all these instances be restarted?
Could you give me an example on how this can work. I mean commands that will make the above case pass. Thanking You. On Wed, Jul 29, 2015 at 10:34 AM, Vijay Partha <vijaysarath...@gmail.com> wrote: > fine will have a look at it. thank you so much. > On 29 Jul 2015 22:56, "Ken Gaillot" <kgail...@redhat.com> wrote: > >> On 07/29/2015 09:24 AM, Vijay Partha wrote: >> > could you give an idea on how active active could be achieved? >> >> Clusters From Scratch gives a simple walk-through of active/active. See >> >> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Clusters_from_Scratch/index.html >> >> The basic components are: >> >> 1. Fencing >> >> 2. Shared storage (DRBD in the walk-through, or could be a SAN or NAS, >> etc.) >> >> 3. Clustered file system (GFS2 in the walk-through) and optionally CLVM >> (if you want to use logical volumes with shared storage); these often >> require DLM (distributed lock manager) as well >> >> 4. Your service (apache in this case) >> >> 5. Some type of load balancer (multicast Ethernet in the walk-through, >> although something like haproxy is more often used in production) >> >> > On 29 Jul 2015 19:52, "Ken Gaillot" <kgail...@redhat.com> wrote: >> > >> >> On 07/29/2015 09:03 AM, Vijay Partha wrote: >> >>> Thanks a lot Ken. for the second case whatever you said , is it >> possible >> >> to >> >>> control even for multiple instances of apache? like i have node 1 >> >> running 2 >> >>> instances of apache and another node running 1 instance in apache. If >> my >> >>> apache server goes down will all these instances be restarted? >> >> >> >> It depends on how you have those instances linked together. >> >> >> >> If they're independent -- one node runs www.A.com and another node >> runs >> >> api.A.com -- then there's no coordination necessary. Each can be >> >> monitored, stopped and started independently of the other. >> >> >> >> If your goal is to do active-passive failover (if the node serving >> >> www.A.com goes down, apache is started on another node), then >> pacemaker >> >> will handle that automatically. >> >> >> >> If your goal is to do active-active load-balancing (every node can >> serve >> >> requests to www.A.com simultaneously), that's a more complicated >> >> configuration, but pacemaker can do it. >> >> >> >> In any of the cases, it's generally not necessary to restart apache on >> >> all nodes. If it's not working on one node, it can be restarted there. >> >> You can manually disable and reenable the service if you want to force >> a >> >> restart everywhere. >> >> >> >>> On Wed, Jul 29, 2015 at 7:26 PM, Ken Gaillot <kgail...@redhat.com> >> >> wrote: >> >>> >> >>>> On 07/29/2015 08:05 AM, Vijay Partha wrote: >> >>>>> Hi. >> >>>>> >> >>>>> Victor, Whatever you said i had tried and got it working. Thank you. >> >>>>> >> >>>>> Could you guys answer the following questions please? >> >>>>> >> >>>>> 1.) I have 2 apache services running on the same node. If the >> services >> >> go >> >>>>> down can pacemaker restart it? >> >>>> >> >>>> Yes, that's what pacemaker is for :) >> >>>> >> >>>> If by two services you mean two server instances of apache, then you >> >>>> would configure two apache resources in pacemaker. If you mean two >> web >> >>>> apps running in one apache server, you'd configure one apache >> resource >> >>>> in pacemaker. >> >>>> >> >>>> You would also need a monitor operation, which tells pacemaker to >> >>>> periodically check the health of the service. >> >>>> >> >>>> The migration-threshold and on-fail options determine what the >> cluster >> >>>> does on failure. See the documentation for possible values, but the >> >>>> default behavior is to try to restart the service on the same node. >> >>>> >> >>>> The documentation for all the options is at >> >>>> >> >>>> >> >> >> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html >> >>>> >> >>>>> 2.) I have 2 apache services running on different nodes. Can i >> control >> >>>> both >> >>>>> the resources from a single node by making use of pacemaker? >> >>>> >> >>>> The various cluster tools work from any node, to affect any or all >> >>>> nodes. Most commonly you'd use one of the high-level cluster shells >> >>>> (crmsh or pcs). They have commands to enable/disable a resource, >> move a >> >>>> resource to a different node, put a node in standby mode, etc. >> > -- With Regards P.Vijay
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