Hi,
The best way to do this would be to use the Cooperative Monitoring
<https://mariadb.com/kb/en/mariadb-maxscale-2106-maxscale-2106-mariadb-monitor/#cooperative-monitoring>
feature which will prevent concurrent failovers from happening. It'll
also help avoid writes going to stale servers if both MaxScales receive
traffic while one of them is doing switchover.
The feature has two modes: the
cooperative_monitoring_locks=majority_of_all which provides consistency
by only allowing writes if more than half of the cluster is available
The other mode is cooperative_monitoring_locks=majority_of_running which
does allow writes even with a single node (i.e. chooses availability
over consistency) but it makes split-brain scenarios possible.
Markus
On 4/13/25 23:13, Richard Reina via discuss wrote:
I have configured a second Maxscale node and was hoping to use it as a
backup in case my other Maxscale node should fail. My question is how
do I deploy it? I take it starting it up and having two Maxscale nodes
working at the same time would be a problem because the both might try
to effectuate failover changes such as promotions simultaneously that
could cause conflicts?
I have written the perl code below that can randomly select a node,
but it would need two working nodes to choose between. How does one
deploy a second node without it conflicting with the first Maxscale node?
my @msn = qw(192.168.0.24 192.168.0.23); # Maxscale Nodes
my $msn = $msn[rand @msn];
my $msn = splice(@msn, rand @msn, 1);
print "I picked: $msn\n";
print "Remaining Maxscale Nodes are: @msn\n";
$dbh =
DBI->connect("DBI:mysql:database=$self->{_db_name};host=$msn;port=4006",$user,
$pwd);
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Markus Mäkelä, Staff Software Engineer
MariaDB plc
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