目前，我正在使用两台服务器：带有magento 1.7的webserver，nginx，php-fpm，用于缓存的redis，以及一个带有5.5.32版本的mysql数据库服务器。 有时会在1-2分钟内继续发生，网络服务器报告错误： SQLSTATE [HY000] [2003]无法连接到lib / Zend / Db / Adapter / Pdo / Mysql.php（96）上'remoteserverip'（4）上的MySQL服务器。 但我用mysql命令检查它连接远程数据库服务器，没关系。 我搜索了谷歌和stackoverflow，没有报道这样的问题。
如我所见，两台服务器的CPU和内存不会过载，http 80连接大约为500。 我也改变了网络服务器：
# cat /etc/sysctl.conf
# System default settings live in /usr/lib/sysctl.d/00-system.conf.
# To override those settings, enter new settings here, or in an /etc/sysctl.d/<name>.conf file
#
# For more information, see sysctl.conf(5) and sysctl.d(5).
# Disable IPv6 autoconf
net.ipv6.conf.all.autoconf = 0
net.ipv6.conf.default.autoconf = 0
net.ipv6.conf.eth0.autoconf = 0
net.ipv6.conf.all.accept_ra = 0
net.ipv6.conf.default.accept_ra = 0
net.ipv6.conf.eth0.accept_ra = 0
#file.file-max = 20000000
fs.file-max = 20000000
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
#net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_fin_timeout = 15
#net.ipv4.tcp_keepalive_time = 1200
net.ipv4.tcp_keepalive_time = 120
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 6
net.ipv4.ip_local_port_range = 1024 65000
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_max_tw_buckets = 5000
vm.overcommit_memory = 1
net.core.somaxconn = 3096
和nginx设置：
user nginx;
worker_processes 32;
error_log /var/log/nginx/error.log;
pid /var/run/nginx.pid;
worker_rlimit_nofile 65535;
events {
worker_connections 65535;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log off;
server_tokens off;
#Adjust client timeouts
#client_max_body_size 50M;
client_body_buffer_size 20k;
client_body_timeout 12;
client_header_timeout 12;
keepalive_timeout 30;
send_timeout 10;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
#Adjust output buffers
fastcgi_buffers 256 16k;
fastcgi_buffer_size 128k;
fastcgi_connect_timeout 3s;
fastcgi_send_timeout 300s;
fastcgi_read_timeout 300s;
fastcgi_busy_buffers_size 256k;
fastcgi_temp_file_write_size 256k;
server_names_hash_bucket_size 100;
gzip on;
gzip_static on;
gzip_disable "msie6";
gzip_proxied any;
gzip_min_length 1100;
#gzip_buffers 16 8k;
gzip_buffers 4 32k;
gzip_http_version 1.1;
gzip_comp_level 6;
gzip_types text/plain text/css application/json application/x-javascript application/javascript text/xml application/xml application/xml+rss text/javascript;
gzip_vary on;
# Load config files from the /etc/nginx/conf.d directory
# The default server is in conf.d/default.conf
open_file_cache max=5000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors off;
keepalive_requests 100000;
reset_timedout_connection on;
include /etc/nginx/conf.d/*.conf;
}
用于DB服务器：
# cat /etc/sysctl.conf
# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and
# sysctl.conf(5) for more details.
# Controls IP packet forwarding
net.ipv4.ip_forward = 0
# Controls source route verification
net.ipv4.conf.default.rp_filter = 1
# Do not accept source routing
net.ipv4.conf.default.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
# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 1
# Disable netfilter on bridges.
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
# Controls the default maxmimum size of a mesage queue
kernel.msgmnb = 65536
# Controls the maximum size of a message, in bytes
kernel.msgmax = 65536
# Controls the maximum shared segment size, in bytes
kernel.shmmax = 68719476736
# Controls the maximum number of shared memory segments, in pages
kernel.shmall = 4294967296
# Disable IPv6 autoconf
net.ipv6.conf.all.autoconf = 0
net.ipv6.conf.default.autoconf = 0
net.ipv6.conf.eth0.autoconf = 0
net.ipv6.conf.all.accept_ra = 0
net.ipv6.conf.default.accept_ra = 0
net.ipv6.conf.eth0.accept_ra = 0
fs.file-max = 200000
# Increase system IP port limits to allow for more connections
net.ipv4.ip_local_port_range = 1024 65000
#net.ipv4.tcp_window_scaling = 0
# number of packets to keep in backlog before the kernel starts dropping them
#net.ipv4.tcp_max_syn_backlog = 1280
# increase socket listen backlog
#net.core.somaxconn = 3240000
#net.ipv4.tcp_max_tw_buckets = 1440000
# Increase TCP buffer sizes
#net.core.rmem_default = 8388608
#net.core.rmem_max = 16777216
#net.core.wmem_max = 16777216
#net.ipv4.tcp_rmem = 4096 87380 16777216
#net.ipv4.tcp_wmem = 4096 65536 16777216
#net.ipv4.tcp_congestion_control = cubic
#Solve TIME_WAIT
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_max_tw_buckets = 5000
和mysql connection_timeout：
mysql> show variables like "%conn%";
+--------------------------+-----------------+
| Variable_name | Value |
+--------------------------+-----------------+
| character_set_connection | utf8 |
| collation_connection | utf8_general_ci |
| connect_timeout | 60 |
| init_connect | |
| max_connect_errors | 10 |
| max_connections | 14000 |
| max_user_connections | 0 |
+--------------------------+-----------------+
首先，我认为这是db服务器不稳定，但mysql远程命令连接正常，只是php mysql_connect报告丢失了连接。 我还更改了sysctl的一些net.ipv4变量，但没有工作。 你能告诉我如何追踪这样的问题吗？ 是否有任何其他调整mysql和Web服务器设置。 提前谢谢。