Lars Marowsky-Bree schrieb:
There is NO working configuration for the quorum server.
The above line does not work.
Well, from my perspective - which of course is the perspective of a user
and not the developer of heartbeat - it works. By "works" I mean, when I
"pull" the cable between the datacenters, the resources are active on
one node only (the node on which it will be active can not be told).
When I put the cable back, the resource may switch sides, but is active
on one node only. So the quorum server makes sure - in this special 2
node setup - that the ressource is active on one node only. In my world
this means "it works" :)
So if a node fails, majority fails, quorum server is used and one node
is granted quorum. The other side looses quorum and shuts down all
ressources (this is the configured policy). If the quorum server fails,
both nodes are active and majority quorum wins, no impact. This kind of
semes like a SPOF free solution - as long as you have your three nodes
in three data centers.
Of course I'm not the heartbeat expert as you are and - please do not
get me wrong - I just don't understand why this "does not work". I want
to understand thats why I'm writing this.
It will only defer to the quorum server in case majority is lost. If the
quorum server than grants quorum, while the other side still has
majority, both sides will have quorum.
Why that ? The other node sees the node failure too and a new voting
session is started - isn't it ? So if the heartbeat is lost, both nodes
start to check the quorum, both fail with majority and ONE is granted
quorum via quorumd. Isn't this as it is expeted work ? Isn't this what
the quorum plugin architecture can be used for ?
(The above line "works" for the very special case of two nodes only, but
that's luck, not design.)
Does "luck" mean, that this behaviour will change in future heartbeat
releases OR that this kind of setup is limited to 2 node setups only ?
Just using the quorumd plugin does not work either.
DO NOT USE THE QUORUM SERVER.
One last - and sorry for the pointed remark - why is it part of the
official heartbeat distribution then (I mean the binary package, but the
source) ?
It is broken. Badly designed. Not integrated with STONITH. Not thought
out. Etc. Etc.
Yes, the quorum server grants quorum to one of its clients. That works.
But that is only like 40% of the whole answer. You DO NOT want to use
it.
And if you do, test it. As in, really test it and work through the
scenarios. You'll find out for yourself.
You have been warned.
Regards,
Lars
Robert
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