i am running a small community ( 6000+ Members ) on a non-virtual 64-bit ubuntu 11.04 system. I am not a Linux-pro, not even advanced, i just tried to setup a webserver, which does nothing special actually. Delivering some dynamic PHP and RoR websites is its task. So it might be that my configuration files do look horrible bad. Also, i might use the wrong vocabulary, so in doubt, please ask. Having a current all-time record of 520 registered users (board-accounts, no system-users) online at same time, average server-load is about 2.0 - 5.0. Meantime (~250 users) average server load value is at about 0.4 - 0.8, sometimes, on some expensive searches a bit higher. everything fine. From time to time however, the load increases up to 120 (120.0, not 12.0 ;) ). In this time, its hard to even connect via SSH, but when i reach the server, and use top/htop/iotop to see whats happening, i cannot identify any process causing high CPU load. iotop tells me about a current reading/writing speed of about approx. 70kb/s, which is quite equal to power-off i think. Memory-Usage is max. at ~ 12GB of 16GB, so swap remains empty. now the odd (at least for me:) waiting some minutes ( since i always get a bit into a panic when this happens, it feels like 5 minutes, but i suppose its more like 20-30 minutes) and the server is back to normal. everything continues as normal. another odd fact: when i run hdparm -tT /dev/sda, i get answer like: /dev/sda: Timing cached reads: 7180 MB in 2.00 seconds = 3591.13 MB/sec Timing buffered disk reads: 348 MB in 3.02 seconds = 115.41 MB/sec when i run the same command while the server is "frozen", the answer is like /dev/sda: <- takes about 5 minutes until this line appears Timing cached reads: 7180 MB in 2.00 seconds = 3591.13 MB/sec <- 5 more minutes Timing buffered disk reads: 348 MB in 3.02 seconds = 115.41 MB/sec <- another 5 minutes so the values are the same, but the quoted time is completely wrong. using time command as prefix also tells me that ~ 15 minutes were used. I searched in dmesg, /var/log/[messages|syslog] - nothing found. /var/log/errors however tells me that: Jul 4 20:28:30 localhost kernel: [19080.671415] INFO: task php5-fpm:27728 blocked for more than 120 seconds. Jul 4 20:28:30 localhost kernel: [19080.671419] "echo 0 /proc/sys/kernel/hung_task_timeout_secs" disables this message. multiple times. now that message does tell me that php5-fpm task was blocked or did block ? - but not if that is the cause or just one of the results of that "freeze". Anyone? to cut the long story short, i dont know where even to start analyzing. So if you can give me any advice by looking at following specs and configs, or ask me to provide more information, i`d be glad. Specs: 6 Core AMD Phenom(tm) II X6 1055T Processor * 16 Gigabyte Ram 2x 1.5 TB Seagate ST1500DL003-9VT16L via SATA 3 via SoftwareRaid (i suppose) Services: (due to service --status-all, those with [ + ]) nginx Webserver 1.0.14 mySQL 5.1.63 Server Ruby on Rails 2.3.11 ( passenger-nginx-module ) php5-fpm 5.3.6-13ubuntu3.7 SSH ido2db Further services: default crontab + nightly backup. syslog-ng Website consists of 2 subdomains, forum. and www. where forum is a phpBB3.x PHP-Board, and www a Ruby on Rails 2.3.11 application (portal). Mini-Note: sometimes i notice that the forum is pretty slow, in contrast to the always-fast (except for this "freeze") portal. Both share the same Database, but the portal is using it read-only. The Webserver is nginx, using phusion passenger module to communicate with the ruby-application. Also, for the forum it communicates with php5-fpm via socket: relevant nginx configuration parts ( with comments/questions starting by ; ) ; in case of freeze due to too high Filesystem activity, maybe adding a limit? #worker_rlimit_nofile 50000; user www-data; ; 6 cores, so i read 6 fits. maybe already wrong? worker_processes 6; pid /var/run/nginx.pid; events { worker_connections 1024; } http { passenger_root /var/lib/gems/1.8/gems/passenger-3.0.11; passenger_ruby /usr/bin/ruby1.8; ; the forum once featured a chat, which was working w/o websockets. ; so it was a hell of pull requests (deactivated now, freeze still happening) keepalive_timeout 65; keepalive_requests 50; gzip on; server { listen 80; server_name www.domain.tld; root /var/www/domain/rails/public; passenger_enabled on; } server { listen 80; server_name forum.domain.tld; location / { root /var/www/domain/forum; index index.php; } ; satic stuff to be handled by nginx location ~* ^/style/.+.(jpg|jpeg|gif|css|png|js|ico|xml)$ { access_log off; expires 30d; root /var/www/domain/forum/; } ; now the php magic, note the "backend"-fcgi_pass location ~ .php$ { fastcgi_split_path_info ^(.+\.php)(.*)$; fastcgi_pass backend; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME /var/www/domain/forum$fastcgi_script_name; include fastcgi_params; fastcgi_param QUERY_STRING $query_string; fastcgi_param REQUEST_METHOD $request_method; fastcgi_param CONTENT_TYPE $content_type; fastcgi_param CONTENT_LENGTH $content_length; fastcgi_intercept_errors on; fastcgi_ignore_client_abort off; fastcgi_connect_timeout 60; fastcgi_send_timeout 180; fastcgi_read_timeout 180; fastcgi_buffer_size 128k; fastcgi_buffers 256 16k; fastcgi_busy_buffers_size 256k; fastcgi_temp_file_write_size 256k; fastcgi_max_temp_file_size 0; } location ~ /\.ht { deny all; } } ;the php5-fpm socket. i read that /dev/shm/ whould be the fastes place for this. bad idea in general? upstream backend { server unix:/dev/shm/phpfpm; } ... } php5-fpm settings (i changed this values due to php5-fpm error log messages higher and higher.. (freeze-problem was there before as well)* listen = /dev/shm/phpfpm user = www-data group = www-data pm = dynamic ; holy, 4000! well, shinking this value to earth-level gave me ; 100s of 502 bad gateway commands. this values were quite stable. ; since there are only max 520 users online i dont get it, why i would need ; as many children as configured here. due to keep-alive maybe? ; asking questions is easier for me since restarting server will make ; my community-members angry ;) pm.max_children = 4000 pm.start_servers = 100 pm.min_spare_servers = 50 pm.max_spare_servers = 150 pm.max_requests = 10 pm.status_path = /status ping.path = /ping ping.response = pong slowlog = log/$pool.log.slow ;should i use rlimit? ;rlimit_files = 1024 chdir = / mysql/my.cnf [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp skip-external-locking bind-address = 127.0.0.1 key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 myisam-recover = BACKUP ; high number, but less gives some phpBB errors. max_connections = 450 table_cache = 512 ; i read twice the cpu cores, bad? thread_concurrency = 12 join_buffer_size = 2084K concurrent_insert = 3 query_cache_limit = 64M query_cache_size = 512M query_cache_type = 1 log_error = /var/log/mysql/error.log log_slow_queries = /var/log/mysql/mysql-slow.log long_query_time = 2 expire_logs_days = 10 max_binlog_size = 100M low_priority_updates=1 [mysqldump] quick quote-names max_allowed_packet = 16M [isamchk] key_buffer = 16M !includedir /etc/mysql/conf.d/ I used smartctl already, hdds seem to be fine. /proc/mdstatus quotes: Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md3 : active raid1 sda3[1] 1459264192 blocks [2/1] [_U] md1 : active raid1 sda1[0] 3911680 blocks [2/1] [U_] unused devices: ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 127727 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 127727 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited I quote some questions in my configuration files, these are not (intentional) directly problem-related, but would be nice for me to know wether they are indeed questionable or done right. One additional Fact: my MYSQL-database is at 12GB size. i dont know if that does matter, but mytop sometimes shows me 4-5 seconds long insert queries, some are 20-30 seconds long. Its just a feeling that i am unable to prove (because i dont know how), but when i disable the database, the freeze seems not to happen. Example: i created a dummy rails application to see the development log. the app made some sql-queries, reads and inserts. the log quite often was like: DbTest Load (0.3ms) SELECT * FROM `db_test` WHERE (`db_test`.`id` = 31722) LIMIT 1 SQL (0.1ms) BEGIN DbTest Update (0.3ms) UPDATE `db_test` SET `updated_at` = '2012-07-04 23:32:34' WHERE `id` = 31722 - now the log stands still for 5-60 seconds. SQL (49.1ms) COMMIT - SQL-Update time in the log does not include freeze time Rendering test/index Completed in 96ms (View: 16, DB: 59) | 200 OK [http://localhost:9000/test] Bad part is: this mini-freeze here only happens from time to time as well. note: meanwhile i cannot even upload files via scp. I currently feel like running form bad to worse and back by googling for my server-problem due to immense lack of knowledge regarding server configurations. It still makes me wonder, why those problems even appear, since 250 users a time is not such a high amount, right? So my questions: whats wrong and how to fix? ;) or: what information can i provide to make the situation more clear? can you point at some critical bad configuration-line which i should consider to catch up in the documentation? are there any tools i can run to see some possible bottlenecks? any further advice? (next to: "pay someone who knows what he does" - its a private project, server costs enough already. :)) Thanks for your time and help. Best Regards, Daniel P.S.: i renamed the configfiles to domain.tld since i dont want to have any % more load to the server until its fixed. might be a exaggeratedly thought.. P.P.S: if i asked a complete duplicate question, sorry. my search results seemed to be quite specific in their own way.