[ClusterLabs] Antw: Re: reproducible split brain

[Digimer]

On 17/03/16 01:57 PM, vija ar wrote:
> root file system is fine ...
> 
> but fencing is not a necessity a cluster shld function without it .. i
> see the issue with corosync which has all been .. a inherent way of not
> working neatly or smoothly ..

Absolutely wrong.

If you have a service that can run on both/all nodes at the same time
without coordination, you don't need a cluster, just run your services
everywhere.

If that's not the case, then you need fencing so that the (surviving)
node(s) can be sure that they know where services are and are not running.

> for e.g. take an issue where the live node is hung in db cluster .. now
> db perspective transactions r not happening and tht is fine as the node
> is having some issue .. now there is no need to fence this hung node but
> just to switch over to passive one .. but tht doesnt happens and fencing
> takes place either by reboot or shut .. which further makes the DB dirty
> or far more than tht in non-recoverable state which wouldnt have happen
> if a normal switch to other node as in cluster would have happened ...
> 
> i see fencing is not a solution its only required to forcefully take
> control which is not the case always
> 
> On Thu, Mar 17, 2016 at 12:49 PM, Ulrich Windl
> <Ulrich.Windl at rz.uni-regensburg.de
> <mailto:Ulrich.Windl at rz.uni-regensburg.de>> wrote:
> 
>     >>> Christopher Harvey <cwh at eml.cc> schrieb am 16.03.2016 um 21:04
>     in Nachricht
>     <1458158684.122207.551267810.11F73AB9 at webmail.messagingengine.com
>     <mailto:1458158684.122207.551267810.11F73AB9 at webmail.messagingengine.com>>:
>     [...]
>     >> > Would stonith solve this problem, or does this look like a bug?
>     >>
>     >> It should, that is its job.
>     >
>     > is there some log I can enable that would say
>     > "ERROR: hey, I would use stonith here, but you have it disabled! your
>     > warranty is void past this point! do not pass go, do not file a bug"?
> 
>     What should the kernel say during boot if the user has not defined a
>     root file system?
> 
>     Maybe the "stonith-enabled=false" setting should be called either
>     "data-corruption-mode=true" or "hang-forever-on-error=true" ;-)
> 
>     Regards,
>     Ulrich
> 
> 
> 
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