Linux - Tools to view disk activity

Here are some tools to find out what process is "eating" your resources:

• iotop
• vmstat
• lsof
• atop
• strace -e trace=open "aplication"

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HAproxy - LoadBalancer - Simple config

I'm testing HAproxy, here is my first simple configuration:
- 1 haproxy server -> Serving 2 backend webservers

Request ---> haproxy:80  ---refered as "webfarm"

                 |          

                / \

            moss1  moss2

Config file: haproxy.cfg

global
        log 127.0.0.1   local0
        log 127.0.0.1   local1 notice
        #log loghost    local0 info
        maxconn 4096
        #nbproc 2
        #chroot /usr/share/haproxy
        user haproxy
        group haproxy
        daemon
        #debug
        #quiet

defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull
        retries 3
        option redispatch
        maxconn 2000
        contimeout      5000
        clitimeout      50000
        srvtimeout      50000

listen  webfarm 0.0.0.0:80
        cookie  SERVERID insert indirect nocache
        balance roundrobin
        server  moss1 10.30.1.61:80 cookie check inter 2000 rise 2 fall 5
        server  moss2 10.30.1.62:80 cookie check inter 2000 rise 2 fall 5

listen admin_stats 0.0.0.0:81
        mode http
        stats uri       /my_stats
        stats realm     Global\ statistics
        stats auth      username:password

        #errorloc       502     http://192.168.114.58/error502.html
        #errorfile      503     /etc/haproxy/errors/503.http
        errorfile       400     /etc/haproxy/errors/400.http
        errorfile       403     /etc/haproxy/errors/403.http
        errorfile       408     /etc/haproxy/errors/408.http
        errorfile       500     /etc/haproxy/errors/500.http
        errorfile       502     /etc/haproxy/errors/502.http
        errorfile       503     /etc/haproxy/errors/503.http
        errorfile       504     /etc/haproxy/errors/504.http

To access haproxy stats:
http://webfarm:81/my_stats

It's working nice, i have to continue tests and try more configuration settings.

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Ubuntu 10.04 - tips - boot in graphic mode

I'm trying Ubuntu (finaly...i wasn't a big fan...but it's growing :)

I installed Lucid Lynx, desktop version, but i'm using it as my second workstation, so i wanted to "tweak it" a little bit.

To boot in text mode, i did some search and found that Ubuntu desktop is configured to work in graphic mode in almost every runlevel

So we can config grub to boot in text mode:

edit /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

add "text"

to the options.

And i also stopped some services:

/etc/rc2.d/

# mv S70bluetooth K70bluetooth

I must confess that the package management of debian based systems is the best (in my humble opinion)

I'm very impressed with "apt-get" ;)

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Logging in Apache - don't log favicon.ico

Apache logs a lot of info, but it can be configured.

Here is a brief description of what i've done to apache config, so that it would not log some hits, for example "favicon.ico", here it goes:

First i altered /etc/apache2/apache2.conf (other systems can be httpd.conf)

I don't want to log agents...
In these lines:

LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined

LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined

I modified to look like this:

LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O" vhost_combined

A lot less info about agent's ;)

Now for the sites, in the file /etc/apache2/sites-available/default i added this:

SetEnvIf Request_URI "^/favicon\.ico$" dontlog

then on the line that has the CustomLog entry:

CustomLog /var/log/apache2/access.log combined env=!dontlog

After this the favicon.ico continues to log in the error.log, so i created a zero size file in /var/www/
# cat /dev/null > favicon.ico

I know it's not the best for debugging but i like it better like this, i think it's better for reading ;)
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