[Pacemaker] Required resources for stateful clones
Serge Dubrouski
sergeyfd at gmail.com
Fri May 20 08:35:33 EDT 2011
On Fri, May 20, 2011 at 3:42 AM, Eamon Roque <Eamon.Roque at lex-com.net>wrote:
> Hi,
>
>
> >> On Thu, May 19, 2011 at 5:05 AM, Eamon Roque <Eamon.Roque at lex-com.net
> >wrote:
>
> >> Hi,
> >>
> >> I've put together a cluster of two nodes running a databank without
> shared
> >> storage. Both nodes replicate data between them, which is taken care of
> by
> >> the databank itself.
> >>
> >> I have a resource for the databank and ip. I then created a stateful
> clone
> >> from the databank resource. I created colocation rules joining the
> >> databank-ms-clone and ip:
> >>
> >> node pgsqltest1
> >> node pgsqltest2
> >> primitive Postgres-IP ocf:heartbeat:IPaddr2 \
> >> params ip="10.19.57.234" cidr_netmask="32" \
> >> op monitor interval="30s" \
> >> meta is-managed="false"
> >> primitive resPostgres ocf:heartbeat:pgsql \
> >> params pgctl="/opt/PostgreSQL/9.0/bin/pg_ctl"
> >>pgdata="/opt/PostgreSQL/9.0/data" psql="/opt/PostgreSQL/9.0/bin/psql"
> >> pgdba="postgres" \
> >> op monitor interval="1min" \
> >> meta is-managed="false"
> >> ms msPostgres resPostgres \
> >> meta master-max="1" master-node-max="1" clone-max="2"
> >> clone-node-max="1" notify="true" target-role="started"
> >> colocation colPostgres inf: Postgres-IP msPostgres:Master
> >> order ordPostgres inf: msPostgres:promote Postgres-IP:start
> >> property $id="cib-bootstrap-options" \
> >> dc-version="1.1.2-2e096a41a5f9e184a1c1537c82c6da1093698eb5" \
> >> cluster-infrastructure="openais" \
> >> expected-quorum-votes="2" \
> >> stonith-enabled="false" \
> >> no-quorum-policy="ignore" \
> >> last-lrm-refresh="1302707146"
> >> rsc_defaults $id="rsc-options" \
> >> resource-stickiness="200"
> >> op_defaults $id="op_defaults-options" \
> >> record-pending="false"
> >>
> >> The normal postgres agent doesn't support this functionality, but I've
> put
> >> together my own using the mysql agent as a model. Before running the
> script
> >> through ocf-tester, I unmanage the postgres resource.
> >>
>
> > Could you show how you implemented promote/demote for pgsql?
>
> Sure, let's start with the ultra-simple "promote" function:
>
> #
> # These variables are higher up in the file, but they will probably help
> with understanding the error of
> # my ways.
>
> CRM_MASTER="${HA_SBIN_DIR}/crm_master"
> ATTRD_UPDATER="${HA_SBIN_DIR}/attrd_updater"
>
> pgsql_promote() {
> local output
> local rc
> local CHECK_PG_SQL
> local COMPLETE_STANDBY_QUERY
> local PROMOTE_SCORE_HIGH
> local MOD_PSQL_M_FORMAT
>
>
> PROMOTE_SCORE_HIGH=1000
> CHECK_PG_SQL="SELECT pg_is_in_recovery()"
> MOD_PSQL_M_FORMAT="$OCF_RESKEY_psql -Atc"
> COMPLETE_STANDBY_QUERY="$MOD_PSQL_M_FORMAT \"$CHECK_PG_SQL\""
>
> output=$(su - $OCF_RESKEY_pgdba -c "$COMPLETE_STANDBY_QUERY" 2>&1)
> echo $output
>
> rc=$?
>
> case $output in
> f)
> ocf_log debug "PostgreSQL Node is running in Master
> mode..."
> return $OCF_RUNNING_MASTER
> ;;
>
> t)
> ocf_log debug "PostgreSQL Node is in Hot_Standby
> mode..."
> return $OCF_SUCCESS
> ;;
>
> *)
> ocf_log err "Critical error in $CHECK_PG_SQL:
> $output"
> return $OCF_ERR_GENERIC
> ;;
> esac
>
> #
> # "Real" promotion is handled here.
> # The trigger file is created and we check for "recovery.conf" on the host.
> # If we can't find it, then the file will be copied from the HA-Config into
> postgres' data folder.
> #
>
> if ! touch $OCF_RESKEY_trigger_file; then
> ocf_log err "$OCF_RESKEY_trigger_file could not be created!"
> return $OCF_ERR_GENERIC
> fi
>
> if [ ! -f $OCF_RESKEY_recovery_conf ]; then
> ocf_log err "$OCF_RESKEY_recovery_conf doesn't exist!"
> cp $OCF_RESKEY_recovery_conf_ersatz $OCF_RESKEY_pgdata
> return $OCF_SUCCESS
> fi
Why do you need this? As far as I know when you switch standby database to
primary using trigger file recovery.conf gets renamed to recovery.done. If
you rename it back DB will be put into standby mode after restart.We are
talking about streaming replication, right?
>
>
> # If both file exist or can be created, then the failover fun can start.
>
> ocf_log info "$OCF_RESKEY_trigger_file was created."
> ocf_log info "$OCF_RESKEY_recovery_conf exists and can be copied to the
> correct location."
>
> # Sometimes, the master needs a bit of time to take the reins. So...
>
> while :
> do
> pgsql_monitor warn
> rc=$?
>
> if [ $rc -eq $OCF_RUNNING_MASTER ]; then
> break;
> fi
>
> ocf_log debug "Postgres Server could not be promoted. Please
> wait..."
>
> sleep 1
>
> done
>
> ocf_log info "Postgres Server has been promoted. Please check on the
> previous master."
>
> #################################
> #Attributes Update: #
> #################################
>
> $ATTRD_UPDATER -n $PGSQL_STATUS_NAME -v \"PRI\" || exit $(echo "Eh!
> Attrd_updater is not working!")
>
> #############################################
> # Resource stickiness pumped up to 1000 : #
> #############################################
>
> $CRM_MASTER -v $PROMOTE_WERT_HOCH || exit $(echo "crm_master could not
> change the Master's status!")
>
> ############
> # Success! #
> ############
>
> return $OCF_SUCCESS
>
> }
>
>
> ######################################################################################################
>
> Thanks!
>
>
And what about demote? Switching standby into primary using trigger files
changes TIMELINE in the DB and that invalidates all other standby databases
as well as previous master database. After that you have to restore them
from a fresh backup made on new master. This particular behavior stopped me
from implementing Master/Slave functionality in pgsql RA so far.
BTW, why pgsql is set to is-managed="false" in your configuration.With this
setting cluster will keep monitoring it but won't take any other actions
AFAIK.
Éamon
>
>
>
> >> Unfortunately, promote/demote doesn't work. ocf-tester tries to use the
> >> "crm_attribute -N pgsql1 -n master-pgrql-replication-agent -l reboot -v
> >> 100", but the (unmanaged) resources don't accept the score change.
> >>
> >> I'm pretty sure that I just need to be hit with a clue stick and would
> be
> >> grateful for any help.
> >>
> >> Thanks,
> >>
> >> ?amon
> >>
>
>
>
> --
> Serge Dubrouski.
> _______________________________________________
> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> Bugs:
> http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
>
>
--
Serge Dubrouski.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.clusterlabs.org/pipermail/pacemaker/attachments/20110520/e1f26230/attachment-0003.html>
More information about the Pacemaker
mailing list