On 02.03.23 14:51, Ulrich Windl wrote:
Gerald Vogt <v...@spamcop.net> schrieb am 02.03.2023 um 14:43 in Nachricht
<9ba5cd78-7b3d-32ef-38cf-5c5632c46...@spamcop.net>:
On 02.03.23 14:30, Ulrich Windl wrote:
Gerald Vogt <v...@spamcop.net> schrieb am 02.03.2023 um 08:41 in Nachricht
<624d0b70-5983-4d21-6777-55be91688...@spamcop.net>:
Hi,
I am setting up a mail relay cluster which main purpose is to maintain
the service ips via IPaddr2 and move them between cluster nodes when
necessary.
The service ips should only be active on nodes which are running all
necessary mail (systemd) services.
So I have set up a resource for each of those services, put them into a
group in order they should start, cloned the group as they are normally
supposed to run on the nodes at all times.
Then I added an order constraint
start mail-services-clone then start mail1-ip
start mail-services-clone then start mail2-ip
and colocations to prefer running the ips on different nodes but only
with the clone running:
colocation add mail2-ip with mail1-ip -1000
colocation mail1-ip with mail-services-clone
colocation mail2-ip with mail-services-clone
as well as a location constraint to prefer running the first ip on the
first node and the second on the second
location mail1-ip prefers ha1=2000
location mail2-ip prefers ha2=2000
Now if I stop pacemaker on one of those nodes, e.g. on node ha2, it's
fine. mail2-ip will be moved immediately to ha3. Good.
However, if pacemaker on ha2 starts up again, it will immediately remove
mail2-ip from ha3 and keep it offline, while the services in the group are
starting on ha2. As the services unfortunately take some time to come
up, mail2-ip is offline for more than a minute.
That is because you wanted "mail2-ip prefers ha2=2000", so if the cluster
_can_ run it there, then it will, even if it's running elsewhere.
Maybe explain what you really want.
As I wrote before: (and I have "fixed" my copy&paste error above to use
consistent resource names now)
1. I want to run all required services on all running nodes at all times.
2. I want two service IPs mail1-ip (ip1) and mail2-ip (ip2) running on
the cluster but only on nodes where all required services are already
running (and not just starting)
3. Both IPs should be running on two different nodes if possible.
4. Preferably mail1-ip should be on node ha1 if ha1 is running with all
required services.
5. Preferably mail2-ip should be on node ha2 if ha1 is running with all
required services.
So most importantly: I want ip resources mail1-ip and mail2-ip only be
active on nodes which are already running all services. They should only
be moved to nodes on which all services are already running.
Hi!
Usually I prefer simple solutions over hightly complex ones.
WOuld it work to use a negative colocation for both IPs, as well as a stickiness of maybe
500, then reducing the "prefer" value to something small as 5 or 10.
Then the IP will stay elsewhere as long as the "basement services" run there.
This approach does not change the order of resource operations; instead it kind
of minimizes them.
In my experience most people overspecify what the cluster should do.
Well, I guess it's not possible using a group. A group resource seems to
be good for a colocation the moment the first resource in the group has
been started (or even: is starting?). For a group which takes longer
time to completely start, that just doesn't work.
So I suppose the only two options would be to ungroup everything and
create colocation constraints between each invidual service and the ip
address. Although I not sure if that would just have the same issue,
just on a smaller scale.
The other alternative would be to start the services through systemd and
make pacemaker a dependency to start only after all services are
running. Pacemaker then only handles the ip addresses...
Thanks,
Gerald
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