Percona Cluster my.cnf with just one node

francesco19 · December 30, 2020, 4:21pm

I want to create a Percona XtraDB cluster with just one node (it’s my dev machine, I need to have the same version as production (so it has to be XtraDB Cluster) but I don’t need more than one node) but I can’t get the my.cnf working.
If I put the same as prod but taking out the information about the other nodes, it just doesn’t start up.
Can someone help me to create the minimum my.cnf file for a XtraB cluster with just one node?

Thank you!

revin · December 30, 2020, 4:31pm

Do you get any errors on the error log? I suspect you are copying the value of wsrep_cluster_address, if you are starting just a single node, I suggest just putting gcom:// as its value. Show us your my.cnf

francesco19 · December 30, 2020, 4:31pm

Hi revin, thanks for your reply.

I do not get any error on the logs, here is what actually happens:


[root&#64;FraDevDb ~]# /etc/init.d/mysql start --wsrep-cluster-address="gcomm://"
Starting MySQL (Percona XtraDB Cluster). ERROR! The server quit without updating PID file (/data/mysql/mysql.pid).
ERROR! MySQL (Percona XtraDB Cluster) server startup failed!

I don’t know where to look at

Here is my.cnf file:


# Generated by Percona Configuration Wizard (http://tools.percona.com/) version REL5-20120208
# Configuration name cube19-auth generated for jon&#64;cube19.com at 2013-06-26 20:49:00

[mysql]

# CLIENT #
port = 3306
socket = /data/mysql/mysql.sock
default-character-set=utf8

[client]

socket = /data/mysql/mysql.sock
default-character-set=utf8

[mysqld]

# GENERAL #
user = mysql
default_storage_engine = InnoDB
socket = /data/mysql/mysql.sock
pid_file = /data/mysql/mysql.pid

# MyISAM #
key_buffer_size = 32M
myisam_recover = FORCE,BACKUP

# SAFETY #
max_allowed_packet = 16M
max_connect_errors = 1000000
skip_name_resolve
sql_mode = STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION,NO_ZERO_DATE,NO_ZERO_IN_DATE,ONLY_FULL_GROUP_BY
sysdate_is_now = 1
innodb = FORCE
innodb_strict_mode = 1

# DATA STORAGE #
datadir = /data/mysql/

# BINARY LOGGING #
log_bin = /data/mysql/mysql-bin
expire_logs_days = 7
sync_binlog = 1

# CACHES AND LIMITS #
tmp_table_size = 32M
max_heap_table_size = 32M
query_cache_type = 0
query_cache_size = 0
max_connections = 500
thread_cache_size = 50
open_files_limit = 65535
table_definition_cache = 1024
table_open_cache = 100

# INNODB #
innodb_flush_method = O_DIRECT
innodb_log_files_in_group = 2
innodb_log_file_size = 64M
innodb_flush_log_at_trx_commit = 1
innodb_file_per_table = 1
innodb_buffer_pool_size = 512M

# LOGGING #
log_error = /data/mysql/mysql-error.log
log_queries_not_using_indexes = 1
slow_query_log = 1
slow_query_log_file = /data/mysql/mysql-slow.log

# UTF8 #
collation-server = utf8_unicode_ci
init-connect='SET NAMES utf8'
character-set-server = utf8

#### Cluster config ####
# Path to Galera library
wsrep_provider = /usr/lib64/libgalera_smm.so

# Cluster connection URL contains the IPs of all the nodes
wsrep_cluster_address = gcomm://

# In order for Galera to work correctly binlog format should be ROW
binlog_format = ROW

# This is a recommended tuning variable for performance
innodb_locks_unsafe_for_binlog = 1

# This changes how InnoDB auto-increment locks are managed and is a requirement for Galera
innodb_autoinc_lock_mode = 2

# IP address of this node
wsrep_node_address = 192.168.10.99

# SST method
wsrep_sst_method = xtrabackup

# Cluster name
wsrep_cluster_name = cluster

# Authentication for SST method
wsrep_sst_auth = "sstuser:hello"

madhusudan · December 30, 2020, 4:31pm

Hi, francesco19

As per u r my.cnf settings the error logs are stored in /data/mysql/mysql-error.log, for finding errors easily open 2 terminals and do tail -f /data/mysql/mysql-error.log in one terminal while u start mysql in another,and no need to start mysql with --wsrep-cluster-address=“gcomm://” if u had already specified in my.cnf file.

francesco19 · December 30, 2020, 4:31pm

Hi madhusudan, thank for your reply.

When I said “i get no error message” I meant in [COLOR=#252C2F]/data/mysql/mysql-error.log. When I try to start mysql nothing is written in that file.

I’m thinking there is something syntactically [COLOR=#252C2F]wrong in my cnf file, since I’ve realised I’ve copied it from a 5.5.33 working instance to my 5.5.34, can be this?

percona.jayj · December 30, 2020, 4:31pm

Sometimes when I face this problem, I try to start mysqld directly to see what errors come out. If you aren’t seeing anything in the error log from mysqld, it’s possible the problem is happening earlier in mysqld_safe

madhusudan · December 30, 2020, 4:31pm

@francesco19,

well there are some other ways to find the root cause, did u try --verbose mode while starting mysql…?, also check whether mysql has permission to write to the error log file!, sometimes we forget to check that.!

francesco19 · December 30, 2020, 4:31pm

Ok, now I am confused. If I run mysqld it starts up! Even with mysqld_safe I see no errors.
If I start it as usual (/etc/init.d/mysql start) it doesn’t work (see post #3).
mysql-error.log has the right permissions, and when I start it with mysqld it writes something in it so it definitely works.
–verbose does not print anything unfortunately
Last check I did was starting it up using “/etc/init.d/mysql start” but without any my.cnf and… it starts up! but with all the default configs of course.
Cannot make it work with the config file!

francesco19 · December 30, 2020, 4:31pm

found the problem:

echo 0 > /selinux/enforce

did the job.
Thanks everybody for helping anyway!

madhusudan · December 30, 2020, 4:31pm

now that’s good news…