postgres@pgtest05f ~ $ psqlpsql (9.4.4)Type "help" for help.pgtest05f/postgres M # show max_replication_slots ; max_replication_slots----------------------- 2(1 row)Time: 0.433 mspgtest05f/postgres M # \qpostgres@pgtest05f ~ $ psqlpsql (9.4.4)Type "help" for help.pgtest05f/postgres M # alter system set max_replication_slots to 3;ALTER SYSTEMTime: 5.309 mspgtest05f/postgres M # \qpostgres@pgtest05f ~ $ /usr/pgsql-9.4/bin/pg_ctl stop -m fast -D /var/lib/pgsql/9.4/data/waiting for server to shut down.... doneserver stoppedpostgres@pgtest05f ~ $ /usr/pgsql-9.4/bin/pg_ctl start -D /var/lib/pgsql/9.4/data/server startingpostgres@pgtest05f ~ $ < 2015-10-26 11:43:25.081 MSK >LOG:  registering background worker "pg_stat_wait collector"< 2015-10-26 11:43:25.082 MSK >LOG:  registering background worker "repl_mon"< 2015-10-26 11:43:25.461 MSK >FATAL:  no more LWLocks availablepostgres@pgtest05f ~ $ vim /var/lib/pgsql/9.4/data/postgresql.auto.confpostgres@pgtest05f ~ $ /usr/pgsql-9.4/bin/pg_ctl start -D /var/lib/pgsql/9.4/data/server startingpostgres@pgtest05f ~ $ < 2015-10-26 11:45:04.244 MSK >LOG:  registering background worker "pg_stat_wait collector"< 2015-10-26 11:45:04.244 MSK >LOG:  registering background worker "repl_mon"< 2015-10-26 11:45:04.447 MSK >LOG:  redirecting log output to logging collector process< 2015-10-26 11:45:04.447 MSK >HINT:  Future log output will appear in directory "pg_log".postgres@pgtest05f ~ $