服务器信息 64GB RAM
英特尔(R) 酷睿(TM) i7-3930K CPU @ 3.20GHz
Mysql 服务器版本：5.6.20-log - MySQL 社区服务器 (GPL)
我在这个服务器上有 20 个网站，就像共享托管一样，我的大网站有 MyIsAM 表
请帮我配置这个 Mysql
这是我的默认 my.cnf
# Example MySQL config file for very large systems.
#
# This is for a large system with memory of 1G-2G where the system runs mainly
# MySQL.
#
# MySQL programs look for option files in a set of
# locations which depend on the deployment platform.
# You can copy this option file to one of those
# locations. For information about these locations, see:
# http://dev.mysql.com/doc/mysql/en/option-files.html
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the "--help" option.
# The following options will be passed to all MySQL clients
[client]
#password = your_password
port = 3306
socket = /var/lib/mysql/mysql.sock
# Here follows entries for some specific programs
# The MySQL server
[mysqld]
bind-address = 127.0.0.1
local-infile = 0
port = 3306
socket = /var/lib/mysql/mysql.sock
skip-external-locking
key_buffer_size = 384M
max_allowed_packet = 1M
table_open_cache = 512
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size = 32M
# Try number of CPU's*2 for thread_concurrency
thread_concurrency = 12
# Don't listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the "enable-named-pipe" option) will render mysqld useless!
#
#skip-networking
# Replication Master Server (default)
# binary logging is required for replication
log-bin=mysql-bin
# required unique id between 1 and 2^32 - 1
# defaults to 1 if master-host is not set
# but will not function as a master if omitted
server-id = 1
# Replication Slave (comment out master section to use this)
#
# To configure this host as a replication slave, you can choose between
# two methods :
#
# 1) Use the CHANGE MASTER TO command (fully described in our manual) -
# the syntax is:
#
# CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
# MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
#
# where you replace <host>, <user>, <password> by quoted strings and
# <port> by the master's port number (3306 by default).
#
# Example:
#
# CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,
# MASTER_USER='joe', MASTER_PASSWORD='secret';
#
# OR
#
# 2) Set the variables below. However, in case you choose this method, then
# start replication for the first time (even unsuccessfully, for example
# if you mistyped the password in master-password and the slave fails to
# connect), the slave will create a master.info file, and any later
# change in this file to the variables' values below will be ignored and
# overridden by the content of the master.info file, unless you shutdown
# the slave server, delete master.info and restart the slaver server.
# For that reason, you may want to leave the lines below untouched
# (commented) and instead use CHANGE MASTER TO (see above)
#
# required unique id between 2 and 2^32 - 1
# (and different from the master)
# defaults to 2 if master-host is set
# but will not function as a slave if omitted
#server-id = 2
#
# The replication master for this slave - required
#master-host = <hostname>
#
# The username the slave will use for authentication when connecting
# to the master - required
#master-user = <username>
#
# The password the slave will authenticate with when connecting to
# the master - required
#master-password = <password>
#
# The port the master is listening on.
# optional - defaults to 3306
#master-port = <port>
#
# binary logging - not required for slaves, but recommended
#log-bin=mysql-bin
#
# binary logging format - mixed recommended
#binlog_format=mixed
# Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /var/lib/mysql
#innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
#innodb_log_group_home_dir = /var/lib/mysql
# You can set .._buffer_pool_size up to 50 - 80 %
# of RAM but beware of setting memory usage too high
#innodb_buffer_pool_size = 384M
#innodb_additional_mem_pool_size = 20M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 100M
#innodb_log_buffer_size = 8M
#innodb_flush_log_at_trx_commit = 1
#innodb_lock_wait_timeout = 50
[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no-auto-rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates
[myisamchk]
key_buffer_size = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M
[mysqlhotcopy]
interactive-timeout
更多信息：我想使用我的 64Gb Ram，我的 mysql 负载很高，网站加载很慢。
答案1
您必须确保至少数据库的索引适合缓存。另外，最好使join缓冲区sort足够大，以防止在磁盘上创建临时表。
我的 32GB RAM 配置如下：
. . . . .
[mysqld]
. . . . .
max_connections = 64
thread_cache_size = 8
thread_concurrency = 8
key_buffer_size = 4G
max_heap_table_size = 128M
join_buffer_size = 32M
sort_buffer_size = 32M
read_buffer_size = 32M
read_rnd_buffer_size = 32M
myisam_sort_buffer_size = 32M
query_cache_limit = 32M
query_cache_size = 64M
table_open_cache = 64
max_allowed_packet = 1M
. . . . .
请记住，key_buffer所有线程协作使用，而每个线程创建join_buffer并sort_buffer供私人使用，因此最大使用的 RAM 量计算为join|sort_buffer_size* max_connections。
当然，RAM 消耗取决于数据库的结构和查询。您的最佳值可能与我的不同。
有一个非常有用的工具，mysqltuner它可以提供许多合理的统计数据以供调整：
-------- Performance Metrics -------------------------------------------------
[--] Up for: 6s (9 q [1.500 qps], 6 conn, TX: 14K, RX: 481)
[--] Reads / Writes: 100% / 0%
[--] Total buffers: 4.2G global + 128.3M per thread (64 max threads)
[OK] Maximum possible memory usage: 12.2G (38% of installed RAM)
[OK] Slow queries: 0% (0/9)
[OK] Highest usage of available connections: 1% (1/64)
[OK] Key buffer size / total MyISAM indexes: 4.0G/2.9G
[!!] Query cache efficiency: 0.0% (0 cached / 4 selects)
[OK] Query cache prunes per day: 0
[OK] Temporary tables created on disk: 0% (0 on disk / 2 total)
[OK] Thread cache hit rate: 83% (1 created / 6 connections)
[OK] Table cache hit rate: 100% (26 open / 0 opened)
[OK] Open file limit used: 0% (21/939K)
[OK] Table locks acquired immediately: 100% (36 immediate / 36 locks)
[OK] InnoDB buffer pool / data size: 128.0M/336.0K
[OK] InnoDB log waits: 0
上述统计数据来自刚刚重启的 mysql 服务器，因此部分值无关紧要。