Ubuntu ramdisk

Mounting ram as a working space which help I/O faster.

#mkdir -p /tmp/ram#sudo mount -t tmpfs -o size=512M tmpfs /tmp/ram/

However, be careful to not exceed the memory you have in the system.


http://www.ubuntuka.com/ubuntu-ramdisk-ramdrive-easy-way/

ubuntu installing mongodb- part II : install php driver

After finishing this part, your php will be able to use mongodb function. 

To install mongodb php driver, first of all we need pecl to install from PHP repository. 

#sudo apt-get install php5-dev php5-cli php-pear

Running pecl to get and install php driver. 

#sudo pecl install mongo

Turn your back to the screen and have a coffee while system compiling the mongo extension. After finishing installation, you will see this : 

Build process completed successfully
Installing '/usr/lib/php5/20090626+lfs/mongo.so'
install ok: channel://pecl.php.net/mongo-1.2.6
configuration option "php_ini" is not set to php.ini location
You should add "extension=mongo.so" to php.ini

Then, edit php.ini  (/etc/php5/cli/php.ini, ubuntu)  and add this line extension=mongo.so.

Reference : http://www.mongodb.org/display/DOCS/PHP+Language+Center

ubuntu installing mongodb- part I : install server

The newest version of mongodb is not in repository of ubuntu. To install newest 2.0, custom repository 10gen is needed.

Add key :

#sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 7F0CEB10

Add repository by creating file name '/etc/apt/sources.list.d/10gen.list'
with this line :
(using upstart)

deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen

You're ready to install :

#apt-get update#apt-get install mongodb-10gen

The mongodb is running in the system. The configuration for mongodb is /etc/mongodb.conf and in /etc/init/mongodb.conf (for startup script)

Reference:
http://www.mongodb.org/display/DOCS/Ubuntu+and+Debian+packages

(link) Nginx "how to" - Fast and Secure webserver

This might be a informative link worth to visit if you are experiencing performance issue with web server. Nginx is an option.
https://calomel.org/nginx.html

mysql commonly use statement

Create table

mysql> CREATE  table if not exists tblname like old_tblname;

INSERT ... SELECT

mysql> INSERT INTO tblname1 SELECT *  from tblname2 where ...;

Empty table

mysql> TRUNCATE table story_longcon_40;

Delete/Drop table

mysql> DROP TABLE tblname; 

Delete/Drop database

mysql> DROP {DATABASE | SCHEMA} [IF EXISTS] db_name

Optimize Table

mysql> OPTIMIZE [NO_WRITE_TO_BINLOG | LOCAL] TABLE tbl_name [, tbl_nam

Delete binary logs 
This will delete the binary log till master.000080

mysql> purge binary logs to 'master-bin.000081';

Start slave

mysql> START SLAVE [thread_type [, thread_type] ... ]

or

mysql> START SLAVE [SQL_THREAD] UNTIL
MASTER_LOG_FILE = 'log_name', MASTER_LOG_POS = log_pos

[MySQL] Backing up data

There are several ways to backing up data
1) Logical backup

* SQL dumps

#mysqldump dbname tblname

Not suitable for huge backup. Both table structure and the data are stored together.(option available)

* Delimited file backups
backing up :

mysql> SELECT * INTO OUTFILE '/tmp/t1.txt'
    -> FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
    -> LINES TERMINATED BY '\n'
    -> FROM test.t1

restore :

mysql> LOAD DATA INFILE '/tmp/t1.txt'
    -> INTO TABLE test1.t1
    -> FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
    -> LINES TERMINATED BY '\n';

*parallel dump: maatkit(mk-parallel-dump)

2) File system snapshot (LVM)
not covered here.

mysql backup/dump/export table schema, definition

1) use mysqldump

server# mysqldump -uroot -p dbname tblname -d 

with this method you will get sql statement. You can use this for backing up table definition as well.

2) create table from another table

mysql> create table if not exists tblname like old_tblname;

with this method you get a copy of table. It is useful if you want to have a another table with the same structure for backing up, testing.

Postfix วิธีการ pipe mail ที่ได้รับ ไปยัง command ต่างๆ

Environment ที่ใช้ทดสอบนะครับ ใช้ Ubuntu 10.04.3, Postfix, Dovecot เป็นหลัก สิ่งที่ต้องการคือ เมื่อมีคนส่ง e-mail มาที่ test@example.com แล้ว ให้ postfix ทำการ pipe email นั้นเข้าสู่โปรแกรม /home/myuser/testperl ซึ่งเป็น perl script ที่ผมเขียนรอไว้ก่อนหน้านี้แล้ว

ทั้งนี้ ตัว postfix ผม config ตัว virtual domains, virtual mailbox ที่ติดต่อกับ mysql server เอาไว้ด้วยนะครับ

เริ่มจาก

• เข้าไปแก้ไข /etc/postfix/main.cf

ที่บรรทัด smtpd_recipient_restrictions เพิ่มคำสั่ง check_recipient_access เข้าไป

smtpd_recipient_restrictions =  

# bypass checks on outgoing mail  

permit_mynetworks  

# reject if not full email address  

reject_non_fqdn_recipient 

# next line rejects if the account/domain does not exist  

# ALSO prevents OPEN RELAY - if missing RELAY is OPEN!!  

# MUST appear before the check_recipient_access  

reject_unauth_destination  

# perform filter access by recipient name  

check_recipient_access hash:/usr/local/etc/postfix/script_filter

• เพิ่ม /etc/postfixscript_filter

test@example.com FILTER support:dummy

• # postmap script_filter จะมีไฟล์ script_filter.db เพิ่มขึ้นมา
• เข้าไปแก้ master.cf

support  unix - n n - - pipe  flags=Rq user=www    argv=/home/myuser/testperl $(sender)$(recipient)

โดยใน perl script จะได้ argument 1 = sender และ argument 2 = receiver

แค่นี้ ระบบก็เรียบร้อยพร้อมใช้งานแล้ว

How to Setup Canon MX350 Series on Ubuntu 11.04 Natty

sudo add-apt-repository ppa:michael-gruz/canon
sudo apt-get update

apt-get install cnijfilter-mx350series

and now you can add printer by
1. Go to search -> printing
2. Add -> Network Printer
3. Canon MX350 Series will appear in left panel
4. Follow the instruction
5. Finish installation

Ubuntu apt-get history

for Ubuntu admin you can track apt-get history at

/var/log/apt/history.log

for a brief

and

for more detail at

/var/log/apt/term.log

mdadm cheat sheet

Mdadm Cheat Sheet

1. Create a new RAID array

Create (mdadm –create) is used to create a new array:

mdadm --create --verbose /dev/md0 --level=1 /dev/sda1 /dev/sdb2

or using the compact notation:

mdadm -Cv /dev/md0 -l1 -n2 /dev/sd[ab]1

2. /etc/mdadm.conf

/etc/mdadm.conf or /etc/mdadm/mdadm.conf (on debian) is the main configuration file for mdadm. After we create our RAID arrays we add them to this file using:

mdadm --detail --scan >> /etc/mdadm.conf

or on debian

mdadm --detail --scan >> /etc/mdadm/mdadm.conf

3. Remove a disk from an array

We can’t remove a disk directly from the array, unless it is failed, so we first have to fail it (if the drive it is failed this is normally already in failed state and this step is not needed):

mdadm --fail /dev/md0 /dev/sda1

and now we can remove it:

mdadm --remove /dev/md0 /dev/sda1

This can be done in a single step using:

mdadm /dev/md0 --fail /dev/sda1 --remove /dev/sda1

4. Add a disk to an existing array

We can add a new disk to an array (replacing a failed one probably):

mdadm --add /dev/md0 /dev/sdb1

5. Verifying the status of the RAID arrays

We can check the status of the arrays on the system with:

cat /proc/mdstat

or

mdadm --detail /dev/md0

The output of this command will look like:

cat /proc/mdstat

Personalities : [raid1]

md0 : active raid1 sdb1[1] sda1[0]

104320 blocks [2/2] [UU]

md1 : active raid1 sdb3[1] sda3[0]

19542976 blocks [2/2] [UU]

md2 : active raid1 sdb4[1] sda4[0]

223504192 blocks [2/2] [UU]

here we can see both drives are used and working fine – U. A failed drive will show as F, while a degraded array will miss the second disk -

Note: while monitoring the status of a RAID rebuild operation using watch can be useful:

watch cat /proc/mdstat

6. Stop and delete a RAID array

If we want to completely remove a raid array we have to stop if first and then remove it:

mdadm --stop /dev/md0

mdadm --remove /dev/md0

and finally we can even delete the superblock from the individual drives:

mdadm --zero-superblock /dev/sda

#Clone partition table

sfdisk -d /dev/sda | sfdisk /dev/sdb

(this will dump the partition table of sda, removing completely the existing partitions on sdb, so be sure you want this before running this command, as it will not warn you at all).

There are many other usages of mdadm particular for each type of RAID level, and I would recommend to use the manual page (man mdadm) or the help (mdadm –help) if you need more details on its usage. Hopefully these quick examples will put you on the fast track with how mdadm works.

Reference :

http://www.ducea.com/2009/03/08/mdadm-cheat-sheet/

ubuntu snmp

I've install cacti to a server which will poll the data from linux box, installed snmp.

To test polling data from cacti to linux box,

#snmpwalk -c public -v 2c [ip-address]

In ubuntu if you want to allow other host to view this data you need to modified

"/etc/default/snmp "

SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -g snmp -I -smux -p /var/run/snmpd.pid [ip-address]'

apache http auth with cgi

If you are using apache http auth with cgi, you have a few more things to do.

You need to enable .htaccess

RewriteEngine On

RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization},L]

mysql open query log without changing my.cnf and restart

Use mysql client connect to server

#show variables like 'general%';

+------------------+----------------------------+

| Variable_name | Value |

+------------------+----------------------------+

| general_log | OFF |

| general_log_file | /var/run/mysqld/mysqld.log |

+------------------+----------------------------+

This 2 vaiables control mysql query logging.

To turn query log on :

SET GLOBAL general_log_file = '/var/log/mysql/sql-log.log' ;

SET GLOBAL general_log = 1

To turn query log off :

SET GLOBAL general_log = 0 ;

SET GLOBAL general_log_file = '/var/run/mysqld/mysqld.log';

Notice: This is for mysql 5.1 only. For mysql 5.0, those variable is not available. you need editing my.cnf and restart.

Page cache and pdflush: Theory of operation and tuning for write-heavy loads

For write-heavy option in system, some kernel option must be adjusted. Here are link to article about some kernel options that might help.

Please refer to : http://www.westnet.com/~gsmith/content/linux-pdflush.htm

perc H200 hardware raid utility in linux

I just bought server coming with hardware raid PERC H200 (Dell).

By the time of this blog, I understand that it use chipset from LSI here are out put from

#lspci --n

LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] [1000:0072] (rev 03)

Unfortunately, the monitoring software for this h/w raid is not open. You have to download sas2ircu bin code. The program will display raid status.

I've downloaded from this link :

http://www.natecarlson.com/2010/08/23/lsi-command-line-utility-for-sas2-non-raid-controllers/#comments

Please visit for usage:

http://hwraid.le-vert.net/wiki/LSIFusionMPTSAS2#a2.Linuxkerneldrivers

find command for deleting empty folder

find ./ -type d -exec rmdir 2>/dev/null {} \;

protecting web access with mod_auth

You can limit web access by password. Apache has module mod_auth* for you. It's easy.

1. create password file

# htpasswd -c /usr/local/apache/passwd/passwords rbowen

New password: mypassword

Re-type new password: mypassword

Adding password for user rbowen

for additional user just remove "-c"

2. add directive to apache (.httaccess or )

AuthType Basic

AuthName "Restricted Files"

# (Following line optional)

AuthBasicProvider file

AuthUserFile /usr/local/apache/passwd/passwords

Require user rbowen

3. Restart apache and have fun!

If you have a problem, please investigate the error_log first.

More information :

http://httpd.apache.org/docs/trunk/howto/auth.html