On 06/06/2013, at 2:50 PM, Vladislav Bogdanov <[email protected]> wrote:
> 06.06.2013 07:31, Andrew Beekhof wrote: >> >> On 06/06/2013, at 2:27 PM, Vladislav Bogdanov <[email protected]> wrote: >> >>> 05.06.2013 02:04, Andrew Beekhof wrote: >>>> >>>> On 05/06/2013, at 5:08 AM, Ferenc Wagner <[email protected]> wrote: >>>> >>>>> Dejan Muhamedagic <[email protected]> writes: >>>>> >>>>>> On Mon, Jun 03, 2013 at 06:19:06PM +0200, Ferenc Wagner wrote: >>>>>> >>>>>>> I've got a script for resource creation, which puts the new resource in >>>>>>> a shadow CIB together with the necessary constraints, runs a simulation >>>>>>> and finally offers to commit the shadow CIB into the live config (by >>>>>>> invoking an interactive crm). This works well. My concern is that if >>>>>>> somebody else (another cluster administrator) changes anything in the >>>>>>> cluster configuration between creation of the shadow copy and the >>>>>>> commit, those changes will be silently reverted (lost) by the commit. >>>>>>> Is there any way to avoid the possibility of this? According to >>>>>>> http://article.gmane.org/gmane.linux.highavailability.pacemaker/11021, >>>>>>> crm provides this functionality for its configure sessions [*], but the >>>>>>> shadow CIB route has good points as well (easier to script via cibadmin, >>>>>>> simulation), which I'd like to use. Any ideas? >>>>>> >>>>>> Record the two epoch attributes of the cib tag at the beginning >>>>>> and check if they changed just before applying the changes. >>>>> >>>>> Maybe I don't understand you right, but isn't this just narrowing the >>>>> time window of the race? After all, that concurrent change can happen >>>>> between the epoch check and the commit, can't it? >>>> >>>> The CIB will refuse to accept any update with a "lower" version: >>>> >>>> >>>> http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html/Pacemaker_Explained/_configuration_version.html >>> >>> I recall that LDAP has similar problem, which is easily worked around >>> with specifying two values, one is original, second is new. >>> That way you tell LDAP server: >>> Replace value Y in attribute X to value Z. And if value is not Y at the >>> moment of modification request, then command fails. >> >> "cibadmin --patch" works this way > > Who is baking new CIB in that case, cibadmin or cib? The patch is applied on the server - so "cib" _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
