[ClusterLabs] Antw: Running two independent clusters

Wed Mar 22 10:40:23 UTC 2017

On 03/22/2017 11:23 AM, Nikhil Utane wrote:
> Hi Ulrich,
>
> It's not an option unfortunately.
> Our product runs on a specialized hardware and provides both the
> services (A & B) that I am referring to. Hence I cannot have service A
> running on some nodes as cluster A and service B running on other
> nodes as cluster B.
> The two services HAVE to run on same node. The catch being service A
> and service B have to be independent of each other.
>
> Hence looking at Container option since we are using that for some
> other product (but not for Pacemaker/Corosync).

I don't know what the official statements are but I have been running up
to 15 Pacemaker (1.1.10)/Corosync-Instances(1.4.7)
with a product years ago using lxc (basically as docker using the
namespaces the linux-kernel provides) and that worked fairly well.
I just had to allow a certain CPU-percentage within a container to be
RT-scheduled for corosync to start properly.

Maybe you could tackle the fencing issue Ulrich has addressed by
introduction of 2 fencing-levels. The 1st one going for
docker-instances and the 2nd (lower prio) going for the nodes. So as
long as fencing the container does the trick the 2nd cluster
won't be involved and once this doesn't work it will go for the node
itself and you will suffer from the probably anyway
inevitable consequences.

Regards,
Klaus

>
> -Regards
> Nikhil
>
>
> On Wed, Mar 22, 2017 at 12:41 PM, Ulrich Windl
> <Ulrich.Windl at rz.uni-regensburg.de
> <mailto:Ulrich.Windl at rz.uni-regensburg.de>> wrote:
>
>     >>> Nikhil Utane <nikhil.subscribed at gmail.com
>     <mailto:nikhil.subscribed at gmail.com>> schrieb am 22.03.2017 um
>     07:48 in
>     Nachricht
>     <CAGNWmJV05-YG+f9VNG0Deu-2xo7Lp+kRQPOn9sWYy7Jz=0gNag at mail.gmail.com
>     <mailto:0gNag at mail.gmail.com>>:
>     > Hi All,
>     >
>     > First of all, let me thank everyone here for providing excellent
>     support
>     > from the time I started evaluating this tool about a year ago.
>     It has
>     > helped me to make a timely and good quality release of our
>     Redundancy
>     > solution using Pacemaker & Corosync. (Three cheers :))
>     >
>     > Now for our next release we have a slightly different ask.
>     > We want to provide Redundancy to two different types of services
>     (we can
>     > call them Service A and Service B) such that all cluster
>     communication for
>     > Service A happens on one network/interface (say VLAN A) and for
>     service B
>     > happens on a different network/interface (say VLAN B). Moreover
>     we do not
>     > want the details of Service A (resource attributes etc) to be
>     seen by
>     > Service B and vice-versa.
>     >
>     > So essentially we want to be able to run two independent
>     clusters. From
>     > what I gathered, we cannot run multiple instances of Pacemaker
>     and Corosync
>     > on same node. I was thinking if we can use Containers and run
>     two isolated
>
>     You conclude from two services that should not see each other that
>     you need to instances of pacemaker on one node. Why?
>     If you want true separation, drop the VLANs, make real networks
>     and two independent clusters.
>     Even if two pacemeaker on one node would work, you habe the
>     problem of fencing, where at least one pacemaker instance will
>     always be surprised badly if fencing takes place. I cannot imaging
>     you want that!
>
>     > instances of Pacemaker + Corosync on same node.
>     > As per https://github.com/davidvossel/pacemaker_docker
>     <https://github.com/davidvossel/pacemaker_docker> it looks do-able.
>     > I wanted to get an opinion on this forum before I can commit
>     that it can be
>     > done.
>
>     Why are you designing it more complicated as necessary?
>
>     >
>     > Please share your views if you have already done this and if
>     there are any
>     > known challenges that I should be familiar with.
>     >
>     > -Thanks
>     > Nikhil
>
>
>
>
>
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