[ClusterLabs] Antw: Re: Set a node attribute for multiple nodes with one command

Kostiantyn Ponomarenko konstantin.ponomarenko at gmail.com
Thu Dec 1 07:04:27 EST 2016


OK, now I see. I still have a few questions.
    1. Is there a good reason to not remove the attribute totally if it is
"deleted"?
    2. Does "attrd_updater" sets attributes to "status" configuration
section only?
    3. Do I need to modify/set "--delay" to 0 before removing or changing
the attribute? Because now I see that previously set delay works when I
delete the attribute (--delete).
    4. Does a delay set only one time work until it's unset (set to 0)?

Thank you,
Kostia

On Wed, Nov 30, 2016 at 10:39 PM, Ken Gaillot <kgaillot at redhat.com> wrote:

> On 11/30/2016 11:31 AM, Kostiantyn Ponomarenko wrote:
> > Hi Ken,
> >
> > I didn't look into the logs, but I experimented with it for a while.
> > Here is what I found.
> >
> > It worked for you because this attribute - "my-attr" - has not ever been
> > set before in that cluster.
> >
> > So if you set an attribute, then remove it, and then set it with
> > "--delay", like:
> >
> >     # attrd_updater -N node-0 -n my-attr --update false --delay 20
> >
> > , this delay (dampening) won't work.
>
> Once set, attributes are not truly deleted -- only their values are
> cleared. And --delay has no effect with --update if the attribute
> already exists, which is what you see above.
>
> To set a delay on an already existing attribute, you have to use
> attrd_updater --update-delay or --update-both.
>
> > Moreover, when you delete this attribute the actual remove will be
> > delayed by that "--delay" which was used when the attribute was set.
> >
> >
> > Thank you,
> > Kostia
> >
> > On Tue, Nov 29, 2016 at 1:08 AM, Ken Gaillot <kgaillot at redhat.com
> > <mailto:kgaillot at redhat.com>> wrote:
> >
> >     On 11/24/2016 05:24 AM, Kostiantyn Ponomarenko wrote:
> >     > Attribute dampening doesn't work for me also.
> >     > To test that I have a script:
> >     >
> >     >     attrd_updater -N node-0 -n my-attr --update false --delay 20
> >     >     sleep 3
> >     >     attrd_updater -N node-0 -n my-attr --update true
> >     >     sleep 7
> >     >     attrd_updater -N node-1 -n my-attr --update true
> >
> >     This sequence works for me -- the attributes are not written to the
> live
> >     CIB until the end of the delay, when both are written at the same
> time.
> >
> >     The remaining issue must be with the policy engine. You could look at
> >     the detail log on the DC when these changes were made; you should see
> >     info-level messages with the CIB change with both values together
> (lines
> >     with "cib_perform_op:   ++" and the attribute values), then
> "Transition
> >     aborted" with "Transient attribute change", then a bunch of
> "pengine:"
> >     lines saying what the cluster wants to do with each resource.
> >
> >     There should be some information about the scores used to place the
> >     resources.
> >
> >     >
> >     > All my resources have this rule in Pacemaker config:
> >     >
> >     >     crm configure location res1-location-rule res1 \
> >     >         rule 0: my-attr eq true \
> >     >         rule -inf: my-attr ne true
> >     >
> >     > On a working two-node cluster I remove "my-attr" from both nodes.
> >     > Then run my script. And all resources start on node-0.
> >     > Am I doing something wrong?
> >     > Or maybe my understanding of an attribute dampening is not correct?
> >     >
> >     > My Pacemaker version is 1.1.13. (heh, not the last one, but it is
> what
> >     > it is ...)
> >     >
> >     > Thank you,
> >     > Kostia
> >     >
> >     > On Wed, Nov 23, 2016 at 7:27 PM, Kostiantyn Ponomarenko
> >     > <konstantin.ponomarenko at gmail.com
> >     <mailto:konstantin.ponomarenko at gmail.com>
> >     > <mailto:konstantin.ponomarenko at gmail.com
> >     <mailto:konstantin.ponomarenko at gmail.com>>> wrote:
> >     >
> >     >     Maybe I am doing something wrong, but I cannot set "status"
> section
> >     >     node attributes to a shadow cib, cluster applies them
> immediately.
> >     >     To try it out I do in a console:
> >     >
> >     >         crm_shadow --create test
> >     >         crm_attribute --type nodes --node node-0 --name
> my-attribute
> >     >     --update 1 --lifetime=reboot
> >     >
> >     >     And this attribute is set to the live cluster configuration
> immediately.
> >     >     What am I doing wrong?
> >     >
> >     >     Thank you,
> >     >     Kostia
> >     >
> >     >     On Tue, Nov 22, 2016 at 11:33 PM, Kostiantyn Ponomarenko
> >     >     <konstantin.ponomarenko at gmail.com
> >     <mailto:konstantin.ponomarenko at gmail.com>
> >     >     <mailto:konstantin.ponomarenko at gmail.com
> >     <mailto:konstantin.ponomarenko at gmail.com>>> wrote:
> >     >
> >     >         Ken,
> >     >         Thank you for the explanation.
> >     >         I will try this low-level way of shadow cib creation
> tomorrow.
> >     >         PS: I will sleep much better with this excellent
> news/idea. =)
> >     >
> >     >         Thank you,
> >     >         Kostia
> >     >
> >     >         On Tue, Nov 22, 2016 at 10:53 PM, Ken Gaillot
> >     >         <kgaillot at redhat.com <mailto:kgaillot at redhat.com>
> >     <mailto:kgaillot at redhat.com <mailto:kgaillot at redhat.com>>> wrote:
> >     >
> >     >             On 11/22/2016 04:39 AM, Kostiantyn Ponomarenko wrote:
> >     >             > Using "shadow cib" in crmsh looks like a good idea,
> but it doesn't work
> >     >             > with node attributes set into "status" section of
> Pacemaker config.
> >     >             > I wonder it it is possible to make it work that way.
> >     >
> >     >             Forgot to mention -- the shadow CIB is probably the
> best way
> >     >             to do this.
> >     >             I don't know if there's a way to do it in crmsh, but
> you can
> >     >             use it with
> >     >             the low-level commands crm_shadow and crm_attribute
> >     >             --lifetime=reboot.
> >     >
> >     >             > Ken,
> >     >             >>> start dampening timer
> >     >             > Could you please elaborate more on this. I don't get
> how I can set this
> >     >             > timer.
> >     >             > Do I need to set this timer for each node?
> >     >             >
> >     >             >
> >     >             > Thank you,
> >     >             > Kostia
> >     >             >
> >     >             > On Mon, Nov 21, 2016 at 9:30 AM, Ulrich Windl
> >     >             > <Ulrich.Windl at rz.uni-regensburg.de
> >     <mailto:Ulrich.Windl at rz.uni-regensburg.de>
> >     >             <mailto:Ulrich.Windl at rz.uni-regensburg.de
> >     <mailto:Ulrich.Windl at rz.uni-regensburg.de>>
> >     >             > <mailto:Ulrich.Windl at rz.uni-regensburg.de
> >     <mailto:Ulrich.Windl at rz.uni-regensburg.de>
> >     >             <mailto:Ulrich.Windl at rz.uni-regensburg.de
> >     <mailto:Ulrich.Windl at rz.uni-regensburg.de>>>> wrote:
> >     >             >
> >     >             >     >>> Ken Gaillot <kgaillot at redhat.com <mailto:
> kgaillot at redhat.com>
> >     >             <mailto:kgaillot at redhat.com
> >     <mailto:kgaillot at redhat.com>> <mailto:kgaillot at redhat.com
> >     <mailto:kgaillot at redhat.com>
> >     >             <mailto:kgaillot at redhat.com <mailto:
> kgaillot at redhat.com>>>>
> >     >             >     schrieb am 18.11.2016 um 16:17 in Nachricht
> >     >             >     <d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com
> >     <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>
> >     >             <mailto:d6f449da-64f8-12ad-
> 00be-e772d8e382ca at redhat.com
> >     <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>>
> >     >             >
> >     >
> >     <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com
> >     <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>
> >     >
> >      <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com
> >     <mailto:d6f449da-64f8-12ad-00be-e772d8e382ca at redhat.com>>>>:
> >     >             >     > On 11/18/2016 08:55 AM, Kostiantyn Ponomarenko
> >     wrote:
> >     >             >     >> Hi folks,
> >     >             >     >>
> >     >             >     >> Is there a way to set a node attribute to the
> >     >             "status" section for few
> >     >             >     >> nodes at the same time?
> >     >             >     >>
> >     >             >     >> In my case there is a node attribute which
> allows
> >     >             some resources to
> >     >             >     >> start in the cluster if it is set.
> >     >             >     >> If I set this node attribute for say two
> >     nodes in a
> >     >             way - one and then
> >     >             >     >> another, than these resources are not
> distributed
> >     >             equally between these
> >     >             >     >> two nodes. That because Pacemaker picks the
> first
> >     >             node to with this
> >     >             >     >> attribute is set and immediately starts all
> >     allowed
> >     >             resources on it. And
> >     >             >     >> this is not the behavior i would like to get.
> >     >             >     >>
> >     >             >     >> Thank you,
> >     >             >     >> Kostia
> >     >             >     >
> >     >             >     > Not that I know of, but it would be a good
> feature
> >     >             to add to
> >     >             >     > attrd_updater and/or crm_attribute.
> >     >             >
> >     >             >     With crm (shell) you don't have transactions for
> >     node
> >     >             attributes,
> >     >             >     but for the configuration. So if you add a
> location
> >     >             restriction
> >     >             >     preventing any resources on your nodes, then
> enable
> >     >             the nodes, and
> >     >             >     then delete the location restrictions in one
> >     >             transaction, you might
> >     >             >     get what you want. It's not elegant, but itt ill
> do.
> >     >             >
> >     >             >     To the crm shell maintainer: Is is difficult to
> >     build
> >     >             transactions
> >     >             >     to node status changes? The problem I see is
> >     this: For
> >     >             configuration
> >     >             >     you always have transactions (requiring
> >     "commit), but
> >     >             for nodes you
> >     >             >     traditionally have non (effects are immediate).
> So
> >     >             you'd need a
> >     >             >     thing like "start transaction" which requires a
> >     >             "commit" or some
> >     >             >     kind of abort later.
> >     >             >
> >     >             >     I also don't know whether a "shadow CIB" would
> help
> >     >             for the original
> >     >             >     problem.
> >     >             >
> >     >             >     Ulrich
> >     >             >
> >     >             >     >
> >     >             >     > You can probably hack it with a dampening
> >     value of a
> >     >             few seconds. If
> >     >             >     > your rule checks for a particular value of the
> >     >             attribute, set all the
> >     >             >     > nodes to a different value first, which will
> write
> >     >             that value and
> >     >             >     start
> >     >             >     > the dampening timer. Then set all the
> >     attributes to
> >     >             the desired value,
> >     >             >     > and they will get written out together when the
> >     >             timer expires.
>
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