[ClusterLabs] pacemaker and cluster hostname reconfiguration

Mon Oct 5 07:18:31 EDT 2020

Riccardo,

> Only working way was to kill/reload corosync/pacemaker couple (I havent
tried with reloading only pacemaker) on both nodes.

I did a migration a long time ago, but haven't experienced any issues,
probably because it was a part of a regular servers update (which includes
reboot).
Any way even if I had to stop all nodes and tolerate to system downtime I
would do this, the benefit is huge. (BTW you may try maintenance-mode which
allows to stop corosync/pacemaker without downtime)

On Mon, Oct 5, 2020 at 9:49 AM Riccardo Manfrin <
riccardo.manfrin at athonet.com> wrote:

> Thanks Igor,
> I'm afraid I tried this path too although I did not mention in the issue.
>
> The procedure I followed was to add the "name" attribute to the node
> list in corosync.conf, with the current hostname, than reboot both nodes
> to start clean, than do the previously described procedure AND sed s///g
> corosync.conf to update the name attribute value to the
> new hostname.
>
> As I rebooted one of the two nodes the stubborn pacemaker brought back
> the old hostnames no matter what. Only working way was
> to kill/reload corosync/pacemaker couple (I havent tried with reloading
> only pacemaker) on both nodes.
>
> Thanks for the suggestion though
> R
>
> On 02/10/20 20:45, Igor Tverdovskiy wrote:
> > Hi Riccardo,
> >
> > As I see you have already handled the issue, but I would recommend using
> > static node names
> > in the corosync.conf instead of reference to hostname. I did so years
> > ago and now I have no issues
> > with hostname changes.
> >
> > e.g.:
> > node {
> >              ring0_addr: 1.1.1.1
> >              name: my.node
> >              nodeid: 123456
> >          }
> >
> > On Thu, Oct 1, 2020 at 10:10 PM Riccardo Manfrin
> > <riccardo.manfrin at athonet.com <mailto:riccardo.manfrin at athonet.com>>
> wrote:
> >
> >     Thank you for your suggestion Ken; I'm indeed on Centos7, but using
> >
> >          hostnamectl set-hostname newHostname
> >
> >     in place of
> >
> >          hostname -f /etc/hostname
> >
> >     didn't have any beneficial effect. As soon as I powered off one of
> the
> >     two nodes, the other one took the old hostnames back and drifted out
> of
> >     sync.
> >
> >     The only way of doing this in the end was
> >
> >     1. rebooting the machine (close in time so that the first new
> corosync
> >     instance coming up never ever sees the old instance from the other
> node,
> >     or it gets the old hostnames again)
> >
> >     2. killing pacemakerd and corosync (and letting systemd bring them
> on up
> >     again).
> >
> >     This second method appears to be the cleanest and more robust, and
> has
> >     the advantage that while primitives/services are unsupervised, they
> are
> >     not reloaded.
> >
> >     I hope this can be of help to someone although I tend to think that
> my
> >     case was really a rare beast not to be seen around.
> >
> >     R
> >
> >     On 01/10/20 16:41, Ken Gaillot wrote:
> >      > Does "uname -n" also revert?
> >      >
> >      > It looks like you're using RHEL 7 or a derivative -- if so, use
> >      > hostnamectl to change the host name. That will make sure it's
> updated
> >      > in the right places.
> >     ________________________________
> >
> >     Riccardo Manfrin
> >     R&D DEPARTMENT
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> Riccardo Manfrin
> R&D DEPARTMENT
> Web<https://www.athonet.com/> | LinkedIn<
> https://www.linkedin.com/company/athonet/>     t +39 (0)444 750045
> e riccardo.manfrin at athonet.com<mailto:riccardo.manfrin at athonet.com>
> [https://www.athonet.com/signature/logo_athonet.png]<
> https://www.athonet.com/>
> ATHONET | Via Cà del Luogo, 6/8 - 36050 Bolzano Vicentino (VI) Italy
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