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From:Michael S. Fischer Date:August 21 2003 1:46am
Subject:RE: MySQL 4.0.13 Memory problem under heavy load
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Keep in mind that Linux will allocate nearly all of its free RAM to the
buffer cache as the kernel opens and reads files to increase filesystem
performance  (cat /proc/meminfo and look at the "buffers" row)  So, lack
of free RAM may not mean what you think it means.  

As for the "too many connections" issues, take a look at the connections
table (mysqladmin proc, or show processlist from the mysql command
prompt).   You may need to raise the connection limit even further.

--Michael

> -----Original Message-----
> From: Kayra Otaner [mailto:kayra@stripped] 
> Sent: Wednesday, August 20, 2003 3:57 PM
> To: mysql@stripped
> Subject: MySQL 4.0.13 Memory problem under heavy load
> 
> 
> Hi all,
> 
> I want to get your opinions on how to increase available/free 
> memory and performance on a heavy volume database server.
> 
> I have MySQL 4.0.13 running on RH 7.2 replicated to another 
> RH 7.2 using same MySQL version. Recently our master database 
> server (2 AMD Cpu + 2Gb memory + 2Gb swap
> space) started to suffer from  memory outages because of 
> heavy load. During day available free memory is changing from 
> 200Mb to 5Mb and when available memory reaches to 5Mb MySQL 
> starts to give 'Too many connections' messages. Db server is 
> working with 45-70 query/second and more than 25,712 
> connection per hour. There are active 10-13 threads serving databases.
> 
> To increase available free memory I've did the following :
> 1- Optimized all tables
> 2- Removed unneccessary/old indexes
> 3- Moved unused databases to replication server
> 4- Increased key_buffer_size from 8Mb to 128Mb
> 5- Have increased max_connection from 100 to 150
> 6- Have increased thread_cache to 5
> 
> This changes helped a bit but still memory is a problem for 
> MySQL. What should I do to prevent 'too many connections' 
> messages and have more memory available on database servers? 
> Should I remove more indexes from tables? Should I increase 
> key_buffer_size to 256Mb or more? Key_buffer_size doesn't 
> look like a problem since key efficiency looks 100% most of the time.
> 
>         
> Thank you for your time
>         
> Kayra Otaner
> 
> 
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