Hi,
I don’t know if this is bug, but we haven’t seen this behaviour before.
We are running a Percona MySQL Slave Server 5.5.28-29.1-log on a Debian Squeeze 6.0.6 (64-Bit) system. When we start the MySQL daemon (without restoring the dumped pool buffer) or stop the slave process the MySQL process is permanently reading from disk:
iostat -kx sda 3Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %utilsda 0,00 0,00 121,67 0,00 1946,67 0,00 32,00 0,98 8,09 8,07 98,13
iotop -P -o -b PID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 1779 be/4 mysql 1873.51 K/s 0.00 B/s 0.00 % 4.92 % mysqld --basedir=/usr --datadir=/srv/mysql --plugin-dir=/usr/lib/mysql/plugin --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/run/mysqld/mysqld.sock --port=6033
mysqladmin processlist±-----±-----±----------±—±--------±-----±------±-----------------±----------±--------------±----------+| Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined | Rows_read |±-----±-----±----------±—±--------±-----±------±-----------------±----------±--------------±----------+| 1133 | root | localhost | | Query | 0 | | show processlist | 0 | 0 | 1 |±-----±-----±----------±—±--------±-----±------±-----------------±----------±--------------±----------+
This slave is a backup server and there are no selects running on this host at all.
The MySQL config file:
cat /etc/mysql/my.cnf [client]port = 6033socket = /var/run/mysqld/mysqld.sock[mysqld_safe]socket = /var/run/mysqld/mysqld.socknice = 0syslog[mysqldump]max_allowed_packet = 16Mquickquote-names[mysqld]user = mysqlpid-file = /var/run/mysqld/mysqld.pidsocket = /var/run/mysqld/mysqld.socktmpdir = /tmpport = 6033datadir = /srv/mysqlbind-address = 0.0.0.0slow_query_log_file = /var/log/mysql/mysql-slow.logslow_query_log = 1long_query_time = 5log_queries_not_using_indexes = 1server-id = 61innodb_data_home_dir = /srv/mysqlinnodb_log_group_home_dir = /srv/ibloginnodb_log_buffer_size = 16Minnodb_data_file_path = ibdata1:512M:autoextendinnodb_buffer_pool_size = 2500Minnodb_additional_mem_pool_size = 64Minnodb_flush_log_at_trx_commit = 2innodb_flush_method = O_DIRECTinnodb_log_files_in_group = 2innodb_log_file_size = 200Minnodb_status_file = 1innodb_file_per_table = 1skip-slave-start = 1max_connections = 100max_binlog_size = 500Mexpire_logs_days = 3relay-log = dbjupiter-relay-binslave_net_timeout = 60log_warnings = 1log_warnings_suppress = '1592’read_only = 1thread_stack = 256Ktable_open_cache = 2048table_definition_cache = 1024thread_cache = 8read_buffer_size = 1Mjoin_buffer_size = 2Mquery_cache_size = 64Mquery_cache_limit = 1Mquery_cache_min_res_unit = 2Kmax_heap_table_size = 64Mtmp_table_size = 64Mkey_buffer_size = 128Mmax_allowed_packet = 16Minnodb_buffer_pool_restore_at_startup = 300innodb_blocking_buffer_pool_restore = 0skip-external-lockingskip-host-cacheskip-name-resolve
What is MySQL doing here or how can I find out?
Thanks in advance.