server backup


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Thread: server backup

  1. #1
    Join Date
    Jan 2010
    Posts
    16

    server backup

    I want to backup my server.
    This is a brand new server and I tried clonezilla but it failed

    I am trying to get a full backup where - I pop in a disk and reboot the server and the o/s on the disk comes into play and I am able to backup the hard disk

    This is a Raid 5 configuration and could you please guide me to some enterprise level backup software either paid or free

    Is this popularly called Bare metal backup

  2. #2
    Join Date
    Jun 2004
    Location
    Newcastle upon Tyne
    Posts
    2,956
    The cloning software in Linux that I know are based on the command "dd" which read sector-by-sector from one disk and write the same on another disk. As such it cannot possibly fail as nothing other than an mirror image of the hard disk is replicated, literally down to byte by byte.

    dd clones empty space same as filled data so I believe Clonezila was designed to economize the time wasted on cloning empty spaces. Therefore Clonezola works fine for a normally stand alone hard disk. It is possible that it breaks down in a Raid 2 or 5 set as the position of every byte has significance because of the stripe operation. Therefore not cloning the empty spaces in this case might upset the Raid system.

    My advise would be to clone each disk by the standard mean of using dd in a terminal, say from a source disk sda to a target disk sde:
    Code:
    dd if=/dev/sda of=/dev/sde bs=32256
    You will need to clone each disk at a time.

    I found cloning a block size equal to a full track of 63 sectors times 512 byes per sector about the optimum. Without specifying the bs parameter dd defaults to 512 bytes per record transfer and take a long time.

    To ensure a perfect cloning you need the target disk either exactly the same size as the source or just larger. This is to satisfy the number of records from the source disk is fully executed. SUch can only be achieved only if the target disk has exact number of sectors as the source. Failing that the target disk cloning will be incomplete and the disk could have a defective partition table.
    Linux user started Jun 2004 - No. 361921
    Using a Linux live CD to clone XP
    To install Linux and keep Windows MBR untouched
    Adding extra Linux & Doing it in a lazy way
    A Grub menu booting 100+ systems & A "Howto" to install and boot 145 systems
    Just cloning tips Just booting tips A collection of booting tips

    Judge asked Linux "You are being charged murdering Windoze by stabbing its heart with a weapon, what was it?" Replied Linux "A Live CD"

  3. #3
    Join Date
    Jan 2010
    Posts
    16
    Say I have a HDD of 300 GB (sda) which I partition as follows
    a) / 50 GB (/dev/sda1)
    b) Swap 50 GB
    c) boot 500 MB
    d) remaining (/dev/sda2)

    Now I take backup of each /dev/sda1 and /dev/sda2

    The /dev/sda1 is 10 percent used and /dev/sda2 is 4 percent used

    Now if I use PING or clonezilla to backup only the partitions sda1 and sda2
    and If I replace the HDD of 300 GB with 290 GB
    will clonezilla / PING be able to restore the partitions considering that
    the space on the new sda1 and sda2 is a little less than original ....
    But considering that usage is 10 percent and 4 percent ...does it matter ?

  4. #4
    Join Date
    Jun 2004
    Location
    Newcastle upon Tyne
    Posts
    2,956
    If you have to clone a bigger hard disk to a small hard disk, like using a 300Gb source on a 290GB target you need to resize the last partition's boundary (using Gparted) so that the number of sectors is within the capacity of the target disk.

    You should clone the whole disk to allow the full compliment of sectors of the smaller disk runs its course or if you know how to calculate the number of records (size as per that specified in the bs parameter) you can use the "count" parameter to specify the exact number of records to be cloned.

    If you don't do the above then your new cloned disk will have a partition table using a boundary larger than the physical disk and no operating system will touch it because none of them know what to do.
    Linux user started Jun 2004 - No. 361921
    Using a Linux live CD to clone XP
    To install Linux and keep Windows MBR untouched
    Adding extra Linux & Doing it in a lazy way
    A Grub menu booting 100+ systems & A "Howto" to install and boot 145 systems
    Just cloning tips Just booting tips A collection of booting tips

    Judge asked Linux "You are being charged murdering Windoze by stabbing its heart with a weapon, what was it?" Replied Linux "A Live CD"

  5. #5
    Join Date
    Jan 2010
    Posts
    16
    This is what I found

    Clonezilla is available in two models
    32 bit and 64 bit amd (amd 64 bit is also suitable for intel 64 bit)

    However both the above do not work for me.

    My drive is configured with physical disk/ logical volume manager lvm2


    So To solve the issue I am trying the following
    I downloaded a number of Linux Live CD's
    none of them worked with the commands

    pvscan, vgscan, vgdisplay, lvdisplay

    only one of them Knoppix works with the above commands

    so I am using Knoppix Live cd 6.7.1 2011-09-14 English version

    I booted the server with the Live cd hence ensuring that the storage array disks (Raid 5)
    are not being used....so No open files
    Next I ran the following commands


    pvscan - this scans for physical volumes
    vgscan - this scans for logical volumes

    I saw that the logical volumes are inactive
    I ran the following command
    vgchange -a y (this will make all logical volumes active)
    next I mounted the external HDD

    dd if=<logical Volume name> | gzip > <path of external hdd>/image.gz

    in my case the exact command was

    dd if=/dev/vg_proddb12/lv_home | gzip > /home/extdisk/back_20121221_dd/image_home.gz

    I hope you guys comment on my solution.

    It has been a long struggle to understand stuff in Linux

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