The PMP was taken later on, after the database was stuck for over an hour. DONOR: set starts around 4:09. However, the logs have been removed from the server, cannot access them anymore. Then a long time nothing was logged and at the moment the database got stuck (confirmed by customer), we got those 2 errors: 130730 6:03:10 [Note] WSREP: Provider paused at a6280df4-f907-11e2-b79a-3fa52bb11ac5:261230 130730 6:04:40 [ERROR] Threadpool could not create additional thread to handle queries, because the number of allowed threads was reached. Increasing 'thread_pool_max_threads' parameter can help in this situation. If 'extra_port' parameter is set, you can still connect to the database with superuser account (it must be TCP connection using extra_port as TCP port) and troubleshoot the situation. A likely cause of pool blocks are clients that lock resources for long time. 'show processlist' or 'show engine innodb status' can give additional hints. 130730 6:04:40 [Note] Threadpool has been blocked for 30 seconds JOINER: 130730 04:09:52 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 130730 04:09:52 mysqld_safe Skipping wsrep-recover for empty datadir: /var/lib/mysql 130730 04:09:52 mysqld_safe Assigning 00000000-0000-0000-0000-000000000000:-1 to wsrep_start_position 130730 4:09:52 [Note] WSREP: wsrep_start_position var submitted: '00000000-0000-0000-0000-000000000000:-1' 130730 4:09:52 [ERROR] An old style --language value with language specific part detected: /usr/share/mysql/english/ 130730 4:09:52 [ERROR] Use --lc-messages-dir without language specific part instead. 130730 4:09:52 [Note] WSREP: Read nil XID from storage engines, skipping position init 130730 4:09:52 [Note] WSREP: wsrep_load(): loading provider library '/usr/lib/libgalera_smm.so' 130730 4:09:52 [Note] WSREP: wsrep_load(): Galera 2.5(r150) by Codership Oy