MariaDB配置优化

Question

所以我想我真的把mariadb的配置文件搞砸了。我正在为apache2和mysql使用专用服务器。我不知道服务器响应时间是因为mysql对查询的响应时间太长，还是它的代码本身。我已经尝试了一些配置生成器，但我觉得它们不工作。以下是专用服务器规范：

Intel C2750 32 GB RAM 256 GB SSD

#
# These groups are read by MariaDB server.
# Use it for options that only the server (but not clients) should see
#
# See the examples of server my.cnf files in /usr/share/mysql/
#

# this is read by the standalone daemon and embedded servers
[server]

# this is only for the mysqld standalone daemon
[mysqld]

#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
# Skip reverse DNS lookup of clients
skip-name-resolve
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
# bind-address      = 127.0.0.1

#
# * Fine Tuning
#
key_buffer_size     = 5048M
key-buffer-size     = 32M
max_allowed_packet  = 2024M
max-allowed-packet  = 16M 
max-connect-errors  = 1000000
thread_stack        = 1024K
thread_cache_size       = 30
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam_recover_options  = BACKUP
max_connections        = 500
table_cache            = 100
table_open_cache = 3000
table_definition_cache = 9000
join_buffer_size = 300K
performance_schema = ON

#thread_concurrency     = 10
max_user_connections    = 455
#
# * Query Cache Configuration
#
query_cache_limit   = 1048M
query_cache_size    = 0
query_cache_type    = 0

slow-query-log = 1
slow-query-log-file = /var/lib/mysql/mysql-slow.log
long_query_time = 1
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Enable the slow query log to see queries with especially long duration
#slow_query_log_file    = /var/log/mysql/mariadb-slow.log
#long_query_time = 10
#log_slow_rate_limit    = 1000
#log_slow_verbosity = query_plan
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
expire_logs_days    = 10
max_binlog_size   = 100M
#binlog_do_db       = include_database_name
#binlog_ignore_db   = exclude_database_name

#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
innodb_buffer_pool_size = 15G
#innodb_s_lock_spin_rounds = 120
#innodb_thread_concurrency = 0
innodb_log_file_size = 3G
innodb_buffer_pool_instances = 25

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         = 4096
table-open-cache               = 100
innodb-flush-method            = O_DIRECT
innodb-log-files-in-group      = 2
innodb-log-file-size           = 512M
innodb-flush-log-at-trx-commit = 2
innodb-file-per-table          = 1
innodb-buffer-pool-size        = 26G

#innodb_buffer_size = 256M
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates you can use for example the GUI tool "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem
#
# Accept only connections using the latest and most secure TLS protocol version.
# ..when MariaDB is compiled with OpenSSL:
# ssl-cipher=TLSv1.2
# ..when MariaDB is compiled with YaSSL (default in Debian):
# ssl=on

#
# * Character sets
#
# MySQL/MariaDB default is Latin1, but in Debian we rather default to the full
# utf8 4-byte character set. See also client.cnf
#
character-set-server  = utf8mb4
collation-server      = utf8mb4_general_ci

#
# * Unix socket authentication plugin is built-in since 10.0.22-6
#
# Needed so the root database user can authenticate without a password but
# only when running as the unix root user.
#
# Also available for other users if required.
# See https://mariadb.com/kb/en/unix_socket-authentication-plugin/

# this is only for embedded server
[embedded]

# This group is only read by MariaDB servers, not by MySQL.
# If you use the same .cnf file for MySQL and MariaDB,
# you can put MariaDB-only options here
[mariadb]

# This group is only read by MariaDB-10.1 servers.
# If you use the same .cnf file for MariaDB of different versions,
# use this group for options that older servers don't understand
[mariadb-10.1]

Answer 1

请记住，如果您不止一次指定一个选项，则该选项的最后一个设置才会生效。您有相当多的重复，这只会导致混淆哪些值是真正有效的。

我建议你做以下几点：

• 对alphabetically中的行进行排序，以查找重复的行(我指的是[mysqld]部分中的行)。
• 选择您真正想要生效的值，并删除具有相同选项的多余设置的其他行。
• 删除将选项设置为默认选项的选项行。
• 删除选项行，对于这些行，您没有特定的理由选择一个非默认值的值。

我注意到你有：

innodb-buffer-pool-size        = 26G

这是你32G内存的81%。假设缓冲池至少额外使用了10%，那么它实际上使用了28.6G。因此，服务器上所有其他内存需求只有3.4G，包括MySQL、Apache、其他进程和操作系统本身。

除了缓冲池之外，MySQL还有其他内存使用，特别是每个连接，并且允许最多500个连接。

您还可以在同一台服务器上运行Apache，当然，任何由Apache运行的web应用程序都是如此。他们也将使用RAM，我无法预测有多少内存，因为这完全取决于您的应用程序代码。Apache允许运行多个并发请求，因此您可能有几十个或数百个web应用程序处理请求的副本。

因此，我想知道您是否使用了过多的RAM，并迫使服务器使用磁盘上的交换空间。对于任何服务器来说，这都是一个性能杀手，因为磁盘(甚至是SSD)比RAM慢一个数量级。

您应该监视top、free或vmstat的内存使用情况。如果看到RAM耗尽，系统使用交换，则应尽量减少RAM的分配，或限制连接数量或Apache请求的数量。您还可以安装更多的RAM，甚至可以将Apache移动到第二个专用服务器。