服务器优化——Sysctl, Apache, MySQL篇

人们常说，服务器的负载能力，很大程度上取决于系统管理员的配置和优化能力。这个是对的，相同的硬件、不同的软件配置，会造成截然不同的效果。下面我将给大家介绍一下如何优化 sysctrl, Apache 以及 MySQL 。请注意，所有配置均为取决于个人，请根据自己的实际情况做调整。 

配置Sysctl 

编辑此文件： 
Code: 

nano -w /etc/sysctl.conf 


如果该文件为空，则输入以下内容，否则请根据情况自己做调整： 
Quote: 

# Controls source route verification 
# Default should work for all interfaces 
net.ipv4.conf.default.rp_filter = 1 
# net.ipv4.conf.all.rp_filter = 1 
# net.ipv4.conf.lo.rp_filter = 1 
# net.ipv4.conf.eth0.rp_filter = 1 

# Disables IP source routing 
# Default should work for all interfaces 
net.ipv4.conf.default.accept_source_route = 0 
# net.ipv4.conf.all.accept_source_route = 0 
# net.ipv4.conf.lo.accept_source_route = 0 
# net.ipv4.conf.eth0.accept_source_route = 0 

# Controls the System Request debugging functionality of the kernel 
kernel.sysrq = 0 

# Controls whether core dumps will append the PID to the core filename. 
# Useful for debugging multi-threaded applications. 
kernel.core_uses_pid = 1 

# Increase maximum amount of memory allocated to shm 
# Only uncomment if needed! 
# kernel.shmmax = 67108864 

# Disable ICMP Redirect Acceptance 
# Default should work for all interfaces 
net.ipv4.conf.default.accept_redirects = 0 
# net.ipv4.conf.all.accept_redirects = 0 
# net.ipv4.conf.lo.accept_redirects = 0 
# net.ipv4.conf.eth0.accept_redirects = 0 

# Enable Log Spoofed Packets, Source Routed Packets, Redirect Packets 
# Default should work for all interfaces 
net.ipv4.conf.default.log_martians = 1 
# net.ipv4.conf.all.log_martians = 1 
# net.ipv4.conf.lo.log_martians = 1 
# net.ipv4.conf.eth0.log_martians = 1 

# Decrease the time default value for tcp_fin_timeout connection 
net.ipv4.tcp_fin_timeout = 25 

# Decrease the time default value for tcp_keepalive_time connection 
net.ipv4.tcp_keepalive_time = 1200 

# Turn on the tcp_window_scaling 
net.ipv4.tcp_window_scaling = 1 

# Turn on the tcp_sack 
net.ipv4.tcp_sack = 1 

# tcp_fack should be on because of sack 
net.ipv4.tcp_fack = 1 

# Turn on the tcp_timestamps 
net.ipv4.tcp_timestamps = 1 

# Enable TCP SYN Cookie Protection 
net.ipv4.tcp_syncookies = 1 

# Enable ignoring broadcasts request 
net.ipv4.icmp_echo_ignore_broadcasts = 1 

# Enable bad error message Protection 
net.ipv4.icmp_ignore_bogus_error_responses = 1 

# Make more local ports available 
# net.ipv4.ip_local_port_range = 1024 65000 

# Set TCP Re-Ordering value in kernel to ‘5′ 
net.ipv4.tcp_reordering = 5 

# Lower syn retry rates 
net.ipv4.tcp_synack_retries = 2 
net.ipv4.tcp_syn_retries = 3 

# Set Max SYN Backlog to ‘2048′ 
net.ipv4.tcp_max_syn_backlog = 2048 

# Various Settings 
net.core.netdev_max_backlog = 1024 

# Increase the maximum number of skb-heads to be cached 
net.core.hot_list_length = 256 

# Increase the tcp-time-wait buckets pool size 
net.ipv4.tcp_max_tw_buckets = 360000 

# This will increase the amount of memory available for socket input/output queues 
net.core.rmem_default = 65535 
net.core.rmem_max = 8388608 
net.ipv4.tcp_rmem = 4096 87380 8388608 
net.core.wmem_default = 65535 
net.core.wmem_max = 8388608 
net.ipv4.tcp_wmem = 4096 65535 8388608 
net.ipv4.tcp_mem = 8388608 8388608 8388608 
net.core.optmem_max = 40960 


如果希望屏蔽别人 ping 你的主机，则加入以下代码： 
Quote: 

# Disable ping requests 
net.ipv4.icmp_echo_ignore_all = 1 


编辑完成后，请执行以下命令使变动立即生效： 
Code: 

/sbin/sysctl -p 
/sbin/sysctl -w net.ipv4.route.flush=1 


MySQL优化 

编辑MySQL的配置文件： 
Code: 

nano /etc/my.cnf 


输入以下内容： 
Quote: 

[mysqld] 
connect_timeout=15 
interactive_timeout=100 
join_buffer_size=1M 
key_buffer=128M 
max_allowed_packet=16M 
max_connections=500 
max_connect_errors=10 
myisam_sort_buffer_size=64M 
read_buffer_size=1M 
read_rnd_buffer_size=768K 
sort_buffer_size=1M 
table_cache=1024 
thread_cache_size=100 
thread_concurrency=4 
wait_timeout=300 
query_cache_size=32M 
query_cache_limit=1M 
query_cache_type=1 
skip-innodb 


请注意，以上配置适用于512M~1024M内存，如内存更大的话请自行做调整。给项目增加内存会加快速度，但是使用过多的内存而导致启用swap的话，会极大的导致系统效率下降。其中 thread_concurrency 这项配置，单CPU的话请设置为2，双CPU的话请设置为4。 

Apache优化 

以下优化适用于 Apache 1.3 系列，如果你用的是 2.0 系列的话，请自行做调整和判断。 

确认 Apache 的配置文件位置并开始编辑： 
Code: 

locate httpd.conf 
nano -w /path/to/httpd.conf 


httpd.conf的文件有许多内容，笔者就拿出需要做优化的： 
Quote: 

KeepAlive On 
MaxKeepAliveRequests 1000 
KeepAliveTimeout 3 

MinSpareServers 8 
MaxSpareServers 13 

MaxRequestsPerChild 50 


将 KeepAliveTimeout 设定到较小的数字将有助于减少服务器上的无用等待链接，一定程度上能增加服务器负载。 

另外，下面这条不算优化，但是是Apache安全相关： 
Quote: 

ServerSignature Off 
ServerTokens ProductOnly 

将 ServerSignature 关闭，并增加 ServerTokens ProductOnly 可以使常人无法检测到Apache的实际版本号，有助于Apache的安全。 

以上所做的这些优化在某种程度上会增强服务器的负载性能。但请注意，最佳的配置是实践出来的。