[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]'