Backup

Backing up and Restore OpenVZ Virtual Vachines with vzdump

Vzdump is a utility to make consistent snapshots of OpenVZ containers (and KVM virtual machines in case you are using Proxmox VE).

It fundamentally creates a tar archive of the container’s private area which also includes the CT configuration files.

The following steps are for Debian Squeeze Linux but vzdump can be used on all other linux distributions

1. Install Vzdump on Deian Squeeze:

apt-get install vzdump

You can also download and install vzdump from the follwing link:

http://download.openvz.org/contrib/utils/vzdump/

wget http://download.openvz.org/contrib/utils/vzdump/vzdump_1.2-4_all.deb


How to Move Your Linux to Another Hard Drive

There are several methods to move Linux to another hard disk on the same server.
But I used Unix dump / restore utility to do this …

Step1. First you need a new hard disk partition in the same way as with previous unit (Linux is running on). I usually use the utility ‘fdisk‘.
Let us suppose that the old drive is /dev/sda and a new one is /dev/sdb.
To view the partition table hda please run ‘fdisk-l  /dev/ sda “which should show something like this:

root@deb:~# fdisk -l /dev/sda

Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0007384e

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        9330    74936320   83  Linux
/dev/sda2            9330        9730     3212289    5  Extended
/dev/sda5            9330        9730     3212288   82  Linux swap

Step2. After this run ‘fdisk /dev/sdb’ and make the same partitions at it. Interactive mode of fdisk utility is well documented and is very intuitive, so I don’t think it would be difficult to perform partitioning.

After this is done, we should make new filesystems at partitions we’ve created:

mkfs -t ext3 /dev/sdb1
mkswap /dev/sdb2

Step3. Now new hard drive preparation is finished and we can proceed with moving Linux to it. Mount new filesystem and change directory to it:

mount /dev/hdb1 /mnt/hdb1
cd /mnt/hdb1

Step4.  Perform moving by command:

dump -0uan -f – / | restore -r -f

When dump/restore procedures are done we should install boot loader to new HDD. Run ‘grub’ utility and execute in it’s console:

root (hd1, 0)
setup (hd1)
quit

Enjoy.


How to Reduce load of backup scripts with nice

Running a backup script on a server system as a webhosting server can produce high load and longer latencys for other processes  or php pages load slow during backup because the backup script takes too much  CPU resources.

On Linux systems there are many utilities available for the programming to set the CPU for a appliaction or a script.

In this tutorial we will use nice.

To reduce the CPU priority, use the following command:

/usr/bin/nice -n 19 /location/of/your/script/backup.sh

The -n parameter can be in the range from -20 to 19.  Lower numbers means higher priority.

 


Some Useful Options for Rsync

Rsync is often used for backup systems, with options such as:

-A --acls       : preserve the ACL, if used

-X --xattrs     : preserve extended attributes, if used

-H --hard-links : detect and preserve hard links

-a --archive    : resources and preserve the usual attributes: symbolic links, devices and special files,
user and group ownership, permissions and schedules

In addition to these stock options, rsync has many other.

Each has its own recipe, but I’d like to share two useful features :


How to Configure MySQL Replication on Debian

1. Configure The Master
First we have to edit /etc/mysql/my.cnf

We have to enable networking for MySQL, and MySQL should listen on all IP addresses, therefore we comment out these lines (if existant):

#skip-networking
#bind-address            = 127.0.0.1

Furthermorewe have to tell MySQL for which database it should write logs,which log file it should use, and we have to specify that this MySQLserver is the master. We want to replicate the database exampledb, so we put the following lines into /etc/mysql/my.cnf:

log-bin = /var/log/mysql/mysql-bin.log

# what database you want to replication

binlog-do-db=exampledb

server-id=1

Then we restart MySQL:

/etc/init.d/mysql restart

Then we log into the MySQL database as root and create a user with replication privileges:

mysql -u root -p
Enter password:

GRANT REPLICATION SLAVE ON *.* TO ‘slave_user’@’%’ IDENTIFIED BY ‘<your_password>’;
FLUSH PRIVILEGES;

Next do this:

USE exampledb; FLUSH TABLES WITH READ LOCK; SHOW MASTER STATUS;

Now leave the MySQL shell:


       


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