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I have two servers one is application server and another is database server. Continuously I am firing query to mysql. At peak time I get error -

Can\'t connect to MySQL server on \'IP Address\' (99)

I couldn't track the issue.

Below is my my.cnf file-

default-time-zone = '+05:30'
# Disabling symbolic-links is recommended to prevent assorted security risks
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,

innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
innodb_buffer_pool_size = 4096M

max_connections = 500
#log_queries_not_using_indexes = 1



key_buffer_size = 2048M

thread_cache_size = 128M

table_cache = 75000
table_definition_cache = 40000
open_files_limit= 75000

sort_buffer_size = 3M 
read_buffer_size = 5M
read_rnd_buffer_size = 3M
myisam_sort_buffer_size = 20M

query_cache_limit = 100M
query_cache_size = 2048M

tmp_table_size = 256M
max_heap_table_size = 256M



At a particular time around 7000 tcp connections in TIME_WAIT and 1 or 2 in ESTABLISHED from application server to database server.

No server load, No Memory Issue, No firewall on both the server.

Please help me to solve this issue.

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"I tried everything": it is often useful in these circumstances to list in your question what you currently consider "everything" to be, both so people don't spend time suggesting things that you have already tried and so other people finding this question later have extra information for a better understanding. – David Spillett Jan 21 '14 at 10:49
I edited the question. Now, What are the steps to track the issue. – user23750 Jan 21 '14 at 10:52
Maybe increase max_connections. – Mihai Jan 21 '14 at 11:34
Informations on your OS would be helpful too – Jeredepp Jan 21 '14 at 11:38
OS - 3.4.57-48.42.amzn1.x86_64, RAM - 15 GB, CPU - 4 – user23750 Jan 21 '14 at 11:51

1 Answer 1

In your configuration you got max-connecions = 500 this means you acutally have 500 connections available to your server, and mysql adds an extraslot for and adminuser who's able to access over a terminal.

So you actually should always be able to connect to your Database even when all connections are used up.

Try to evaluate who/what is using up your administration connection, and get rid of it. Reasons i encountered are poorly written cronjobs which connect via shellscript to your DB (for example a self written backupscript) this takes a long time to run and locks you out of your Database.

Also check your open files limit on your OS in most distribution these values need to be raised when you have some heavy traffic on your server.

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Suddenly I get this error and whenever I check ESTABLISHED connections it remains always less than 50. I think I am not running out of connection. open files limit already set to 40k. – user23750 Jan 21 '14 at 12:01
how are you trying to acces your DB? (terminal, software on remote ....) – Jeredepp Jan 21 '14 at 12:39
we are using by software – user23750 Jan 23 '14 at 6:21
When you're using software, this counts as normal connection (correct me if i'm wrong), and you won't be able to connect if max-connections is reached. Check your webserver logs for hints on your error, for example 'too many connections' – Jeredepp Jan 24 '14 at 7:02

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