[ClusterLabs] [Question] Question about mysql RA.

[renayama19661014 at ybb.ne.jp]

Hi All,

I contributed a patch several times about mysql, too.

I did not mind it very much before, but mysql RA makes next move.

Step1) Constitute a cluster using mysql in Pacemaker.
Step2) The mysql process kill by signal SIGKILL.
Step3) Stop Pacemaker before monitor error occurs and stop mysql

As a result, mysql RA causes trouble in stop.
By this trouble, Pacemaker does not stop until escalation.


The cause is processing unlike pgsql RA.
When a process of pid does not exist, in the case of a stop not to go by way of monitor trouble, mysql RA produces ERR_GENERIC.
When a process of pid does not exist, pgsql becomes the success of the stop.

---------------------------------------------------------
* mysql
(snip)
mysql_monitor() {
    local rc
    local status_loglevel="err"

    # Set loglevel to info during probe
    if ocf_is_probe; then
        status_loglevel="info"
    fi
 
    mysql_common_status $status_loglevel

    rc=$?

    # TODO: check max connections error

    # If status returned an error, return that immediately
    if [ $rc -ne $OCF_SUCCESS ]; then
        return $rc
    fi
(snip)
mysql_stop() {
    if ocf_is_ms; then
        # clear preference for becoming master
        $CRM_MASTER -D

        # Remove VIP capability
        set_reader_attr 0
    fi

    mysql_common_stop
}
(snip)

* mysql-common.sh
(snip)
mysql_common_status() {
    local loglevel=$1
    local pid=$2
    if [ -z "$pid" ]; then
        if [ ! -e $OCF_RESKEY_pid ]; then
            ocf_log $loglevel "MySQL is not running"
            return $OCF_NOT_RUNNING;
        fi

        pid=`cat $OCF_RESKEY_pid`;
    fi
    if [ -d /proc -a -d /proc/1 ]; then
        [ "u$pid" != "u" -a -d /proc/$pid ]
    else
        kill -s 0 $pid >/dev/null 2>&1
    fi

    if [ $? -eq 0 ]; then
        return $OCF_SUCCESS;
    else
        ocf_log $loglevel "MySQL not running: removing old PID file"
        rm -f $OCF_RESKEY_pid
        return $OCF_NOT_RUNNING;
    fi
}
(snip)
mysql_common_stop()
{
    local pid
    local rc

    if [ ! -f $OCF_RESKEY_pid ]; then
        ocf_log info "MySQL is not running"
        return $OCF_SUCCESS
    fi

    pid=`cat $OCF_RESKEY_pid 2> /dev/null `
    /bin/kill $pid > /dev/null
    rc=$?
    if [ $rc != 0 ]; then
        ocf_exit_reason "MySQL couldn't be stopped"
        return $OCF_ERR_GENERIC
    fi
(snip)
---------------------------------------------------------

The mysql RA does such a code from old days.
 * http://hg.linux-ha.org/agents/file/67234f982ab7/heartbeat/mysql

Does mysql RA know the reason becoming this made?
Possibly is it a factor to be conscious of mysql cluster?

I think about a patch of this movement of mysql RA.
I want to know the detailed reason.

Best Regards,
Hideo Yamauchi.