Fairly new to Linux. Have always worked on managed dedicated boxes with WHM or Plesk, but I decided to have a go at tackling things myself.

I'm running a small Drupal site that sees ~600 visitors a day. It seems my IO have been averaging at around 2-3k, but it spiked to 7k earlier today. I ran the cmd "free" and this is the output:

total used free shared buffers cached
Mem: 435296 429280 6016 0 15336 16980
-/+ buffers/cache: 396964 38332
Swap: 262140 156372 105768


So it seems that the system is always swapping. I run the cmd "top" but there is nothing using more than 1% of memory. When I load a page on the site, apache/httpd comes in and eats up about 7-11%. But how does that explain that I have virtually no free memory?

Here is my my.cnf file

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

# To allow mysqld to connect to a MySQL Cluster management daemon, uncomment
# these lines and adjust the connectstring as needed.
#ndbcluster
#ndb-connectstring="nodeid=4;host=localhost:1186"

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

[ndbd]
# If you are running a MySQL Cluster storage daemon (ndbd) on this machine,
# adjust its connection to the management daemon here.
# Note: ndbd init script requires this to include nodeid!
connect-string="nodeid=2;host=localhost:1186"

[ndb_mgm]
# connection string for MySQL Cluster management tool
connect-string="host=localhost:1186"

I could copy php.ini but it is large. Mem limit is set to 128mb (drupal is a memory hog), but I don't see how that could be the issue?


Hope you have patience for someone trying to learn. Thank you.[/code]

ps aux --sort -rss

will sort processes by ram usage.

What's your apache MaxClients value?

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Are you running Ubuntu and saslauthd by any chance?

I'm running CentOS

obs:

I went into httpd.conf and changed my prefork settings to this:

<IfModule prefork.c>
StartServers 2
MinSpareServers 2
MaxSpareServers 4
ServerLimit 13
MaxClients 13
MaxRequestsPerChild 4000
</IfModule>

My linode has 512MB RAM, and each apache process eats up ~30MB. So I figured 13 for max would be a good number. I also lowered the others to make more 'sense'. Not sure what ServerLimit is revelant to, but I set it to match MaxClients. I didn't touch max requests though.

There is also a similar set of settings that I did not modify:

<IfModule worker.c>
StartServers 2
MaxClients 150
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 25
MaxRequestsPerChild 0
</IfModule>

How can I test to see if worker.c is being used instead?

Thank you!!!!

apache2 -l (or maybe it's httpd -l in centos?) will list compiled in modules, you'll see worker.c or prefork.c in that list.

apache2 -V is a similar list of compiled options, a little more verbose, in that one, look for the APACHE_MPM_DIR

Cool, looks like it was compiled with prefork. I also noticed memory usage is way down and no thrashing at all since the change

There you go problem solved, it's almost always max clients when someone chirps up about ram on a new lamp stack!

_________________
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How to ask for help
1. Give details of your problem
2. Post any errors
3. Post relevant logs.
4. Don't hide details i.e. your domain, it just makes things harder
5. Be polite or you'll be eaten by a grue