[CentOS] backup with dd

Les Mikesell lesmikesell at gmail.com
Wed Jun 25 18:46:36 UTC 2008

Hiep Nguyen wrote:
> hi all,
> i have a centos box and would like to back up just in case the hard 
> drive fail.  one way to do this is duplicate the image of the hard 
> drive, so if the hard drive fail, just remove it and put mirrored hard 
> drive and done.
> here my system info:
> uname -a
> Linux jadenet.jadesterling.com 2.6.9-22.0.2.EL #1 Tue Jan 17 06:51:40 
> CST 2006 i686 i686 i386 GNU/Linux
> df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/mapper/VolGroup00-LogVol00
>                        37G   15G   20G  43% /
> /dev/hda1              99M  8.9M   85M  10% /boot
> none                  188M     0  188M   0% /dev/shm
> i'm looking into dd, but is there anything better than dd?
> by the way, i would like to use external hard drive via usb to do mirror 
> image.

dd has the advantage of creating a disk that is instantly usable.  The 
disadvantages are that you have to have it unmounted while making the 
copy (boot from a CD) and it takes a long time to complete since you 
have to copy even the unused blocks.  There is also the possibility that 
your working disk will develop a bad spot that you don't realize until 
you hit it during the copy, leaving you with 2 bad disks (rotating 2 
copies would avoid this issue).

Clonezilla-live is a boot-from CD linux that will copy just the used 
portions of the disk and can save to another disk or image files on 
local disks or over the network.  I'd recommend it over dd, but maybe 
someone has a way to do LVM snapshots so the copy can be done without a 

   Les Mikesell
    lesmikesell at gmail.com

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