[SATLUG] Live backup / hot imaging software for Linux?

Bruce Dubbs bruce.dubbs at gmail.com
Thu Feb 3 17:13:15 CST 2011


David Salisbury wrote:
>  > That can be a bit tricky since other processes may be updating the 
> partition as
>  > you are copying.  You really don't want to copy the partition 
> superblock and related
>  > data.
> 
> But, if I'm wanting a full image of the drive (so as to just plug the 
> backup in and go in case of drive failure) don't I need the partition 
> superblock and structure data as well?  

No.  It is created when the partition is formatted.

> I know that the partition 
> content can change during the copy, and with the data/processes on this 
> drive/system that's OK.  I guess I'd just like to be able to make a 
> full, fully-bootable copy of a drive without having to shut down the 
> machine that it's running on, if I can.
> 
> Oh, and I'd tried the copy command before with "cp /dev/hda /dev/hdb",

You don't want to specify devices.  Use files.  I have used tar to copy 
a root partition to a file and then to another system.  A few files need 
to be changed for hostname, ip address, etc.

> but sometimes the result in /dev/hdb would work and would boot and 
> sometimes it wouldn't, even after booting with a rescue disc and 
> repairing anything bootloader-related.  I was just curious if there's 
> something that will do this type of backup on a more "consistent" basis.

Yes.  Copy the files:

cd /
mount /dev/hdb /mnt
tar --one-file-system /mnt -cf - . | (cd /mnt; tar -xf -)
umount /mnt

Note that you do not want to copy some mounts like /proc, /sys, etc.
/dev could be copied, but it is generally populated dynamically by udev.

   -- Bruce






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