[Xen-users] Re: How to Backup and Restore MBR within Logical Volumes?

Mr. Teo En Ming (Zhang Enming) space.time.universe at gmail.com
Fri Nov 13 03:17:00 UTC 2009


On Fri, Nov 13, 2009 at 5:40 AM, Sergey Vlasov <vsu at altlinux.ru> wrote:

> On Fri, Nov 13, 2009 at 12:57:22AM +0800, Mr. Teo En Ming (Zhang Enming)
> wrote:
> [...]
> > # VM 11: Rocks 5.1 x86_64 HPC Compute Cluster HVM domU
> >
> > kpartx -av /dev/virtualmachines/rocks0001
> >
> > dd if=/dev/virtualmachines/rocks0001 of=$DEST/rocks0001.mbr bs=512
> count=1
> >
> > partimage -d -M -b -z1 save /dev/mapper/virtualmachines-rocks0001p1
> > $DEST/virtualmachines-rocks0001p1.img
> >
> > partimage -d -M -b -z1 save /dev/mapper/virtualmachines-rocks0001p2
> > $DEST/virtualmachines-rocks0001p2.img
> >
> > partimage -d -M -b -z1 save /dev/mapper/virtualmachines-rocks0001p5
> > $DEST/virtualmachines-rocks0001p5.img
>
> Note that this VM (and some other VMs listed in your script) uses
> logical partitions.  In this case just saving a copy of MBR will not
> be enough to save partition layout - MBR describes only 4 primary
> partitions, and restoring just MBR will not restore extended
> partitions.
>
> One way to backup the complete partition layout is by saving also
> the output of "sfdisk -d $device"; the resulting file can be used as
> input to sfdisk to restore all partitions, including logical ones.
> Saving MBR is still needed together with sfdisk, because it saves
> the boot code (used for HVM) and CHS geometry information (which can
> be used during boot in some cases).
>
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>
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>



Thank you for pointing this out. Otherwise I would made incomplete backups.

Would it be best practice to always backup both the MBR and the partition
geometry using sfdisk whenever cloning our harddisks on desktops and
servers?

Besides sfdisk, there are also other partitioning tools like fdisk, cfdisk,
and parted.

Could these other tools also be used for backing up the partition geometry
like sfdisk?

Thank you.

-- 
Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical
Engineering)
Alma Maters:
(1) Singapore Polytechnic
(2) National University of Singapore
My Primary Blog: http://teo-en-ming-aka-zhang-enming.blogspot.com
My Secondary Blog: http://enmingteo.wordpress.com
My Youtube videos: http://www.youtube.com/user/enmingteo
Email: space.time.universe at gmail.com
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