[Pacemaker] stickiness weirdness please explain

[Jelle de Jong]

Dear Dan,

Thank you again for taking the time to answer my question, it was very
helpful.

On 24-02-11 11:38, Dan Frincu wrote:
> The way I used the crm move command was not to specify the node name. I 
> can't remember now why I did that (probably because I also used it on a 
> 2-node cluster), but the logic was use crm move groupname, and it will 
> create a location constraint preventing the resources from the group 
> from running on the node that's currently primary. After the migration 
> of the resources has occured, in order to remove the location constraint 
> (e.g.: allow the resources to move back if necessary) you must either 
> remove the location constraint from the cib or use crm unmove groupname, 
> I used the unmove command.

Removing the hostname did the trick and it worked directly as expected!

I followed the instructions in Cluster_from_Scratch.pdf chapter
"Manually Moving Resources Around the Cluster" with the example command
"crm resource move WebSite pcmk-1" but it seems running crm resource
move rg_iscsi on the node running the resource is the way to go, the
unmove was explained perfect in the rest of the chapters.

> If the move command somehow doesn't work, you might want to take a look 
> if you've configured resource level fencing for DRBD, 
> http://www.drbd.org/users-guide/s-pacemaker-fencing.html
> The fence peer handler will add a constraint in some cases (such as when 
> you put a node in standby) preventing the DRBD resource to run. When you 
> bring a node online, and there have been disk changes and DRBD has to 
> sync some data, until the data is synced the constraint is still there, 
> so issuing a crm resource move while DRBD is syncing won't have the 
> expected outcome (again the reference to being finger happy on the 
> keyboard). After the sync is done, the crm-unfence-peer.sh removes the 
> constraint, then the move command will work.\

Thank you for that url! It seems I missed it when reading the great
online DRBD manual.

I now added the following to my common drbd config and run drbdadm
adjust all on both nodes;

# disk
fencing resource-only;

# handlers
fence-peer "/usr/lib/drbd/crm-fence-peer.sh";
split-brain "/usr/lib/drbd/notify-split-brain.sh root";
out-of-sync "/usr/lib/drbd/notify-out-of-sync.sh root";
after-resync-target "/usr/lib/drbd/crm-unfence-peer.sh";

This will probalby solve teh time-warp I saw when i forced the ip to be
located on the finley host on previous tastings I done.

So to summarize, thank you Dan, for help getting my group, collocation
and order resources better, making crm work as expected, solving my
stickiness issues, and helping me to make the resource move working!

With kind regards,

Jelle de Jong