Changes between Version 3 and Version 4 of HostingServerSetupRecommendations

Timestamp:

Aug 27, 2010, 6:59:35 AM (14 years ago)

Author:

AlexT

Comment:

--

HostingServerSetupRecommendations

@@ -12 +12 @@
 == MySQL ==
 
+First you need to check if query_cache is enabled on your server. It was noticed that 80% of all SELECT queries are taken from query_cache when it is enabled, so if it is disabled on your server - mysql performance is '''5''' times slower ! 
+
+To check this go to phpMysqlAdmin tool (in most cases it is in your whm panel -> SQL Services -> phpMyAdmin). Then click "Variables" tab.
+"query cache size" must be at lesat 16M, "query cache type" must be ON and "query cache limit" value should be around 1M.
+Example of good configuration:
+
+ [[Image(hssr-mysql-1-query-cache.jpg)]]
+
+After you realized that you need to change these settings you need to edit "my.cnf" file on your server (in most cases it in in "/etc" folder) and add the foollowing lines in "[mysqld]" section of the file, if the same configuration options already exists it is better to comment out old ones (with hash # symbol ) and add new ones near them:
+
+{{{
+[mysqld]
+query_cache_limit = 1M
+query_cache_size = 32M
+}}}
+
+You need to restart mysql server to apply the changes, you can do it from whm panel or from command line, most common command line for linux servers is:
+
+{{{
+/etc/init.s/mysql restart
+}}}
+
+This most critical configuration options. Other useful options must be enabled too - "key buffer size", "max heap table size", "tmp table size", "thread_cache" are some of them. But exact values varies from server from server, for example for dedicated or VPS server with 1Gb RAM and one dolphin site, these values maybe like this:
+
+{{{
 [mysqld]
 
@@ -24 +49 @@
 thread_cache = 128
 
-First you need to check if query_cache is enabled on your server. It was noticed that 80% of all SELECT queries are taken from query_cache when it is enabled, so if it is disabled on your server - mysql performance is '''5''' times slower ! 
-
-To check this go to phpMysqlAdmin tool (in most cases it is in your whm panel -> SQL Services -> phpMyAdmin). Then click "Variables" tab.
-"query cache size" must be at lesat 16M, "query cache type" must be ON and "query cache limit" value should be around 1M.
-Example of good configuration:
-
- [[Image(hssr-mysql-1-query-cache.jpg)]]
-
-After you realized that you need to change these settings you need to edit "my.cnf" file on your server (in most cases it in in "/etc" folder) and add the foollowing lines in "[mysqld]" section of the file, if the same configuration options already exists it is better to comment out old ones (with hash # symbol ) and add new ones near them:
-
-{{{
-[mysqld]
-
-query_cache_limit = 1M
-query_cache_size = 32M
 }}}
 
-This most critical configuration options
+There is already a tool in phpMyAdmin which can help you with deciding what configuration values need to be changed. Go to phpMyAdmin and open "Status" tab, look through this page and pay attention to red values. There is a comment near each value you can use as a guide in changing particular MySQL option. Keep in mind that this is values are collected during some time, so if you change some value it is better to wait at least 1 day until new data is collected for analysis. After MySQL restarted this data is collected from the scratch.
 
+This is an example on many queries becomes cached after introducing "query cache":
 
+[[Image(hssr-mysql-2-queries-day.png)]]
+
+1 day is showed on the graph, in the beginning cache was disabled then cache was enabled - pink zpne shows SELECT queries which are taken from cache. So, benefits are obvious !