On Thu, Nov 12, 2009 at 10:45 AM, Bryn M. Reeves <b...@redhat.com> wrote:
> On Thu, 2009-11-12 at 09:23 +0000, Mr. Teo En Ming (Zhang Enming) wrote: > > Hi All, > > > > I have several Xen virtual machines within logical volumes using LVM2. > > I did not use disk images for performance reasons. > > > > Conventionally, if I want to clone my virtual machines, I have to dd > > the LV to an image file. But this consumes a lot of time and harddisk > > space. > > > > So, instead of doing that, I want to use losetup and kpartx with my > > logical volumes, which contain operating systems of virtual machines. > > > > I can backup the filesystems of a virtual machine in this way: > > > > # losetup /dev/loop1 /dev/virtualmachines/windows7-x64 > > What's the point of adding a loopback device on top of the LV? Running > kpartx on the LV itself will work just fine and this just adds an > unnecessary layer of overhead and complexity unless I am missing > something. > > > dd if=/dev/hda of=mbr.hda bs=512 count=1 > > > > Because /dev/hda resides in a logical volume. The logical volume is a > > virtual harddisk for my virtual machine. > > Assuming that the LV given above is a whole-disk image containing a DOS > MBR partition table: > > dd if=/dev/virtualmachines/windows7-x64 of=/tmp.mbr.img bs=512 count=1 > > You could also do the same with the loopN device that you set up > earlier, although I still don't see the need for that step. > > > 1) re-create the physical volume (PV) > > > > 2) re-create the volume group > > > > 3) assign the PV to the volume group > > > > 4) restore the LVM metadata, i.e. the configuration files for all the > > logical volumes > > > > 5) restore the MBR of my domU > > > > 6) restore the filesystems of my domU > > Should work fine, just be sure to test each step so that you are > confident and comfortable with it before you find yourself needing to do > this in anger. > > Regards, > Bryn. > > > -- > fedora-list mailing list > fedora-list@redhat.com > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list > Guidelines: > http://fedoraproject.org/wiki/Communicate/MailingListGuidelines > Hi Bryn, I have just tried an experiment without the losetup step. I have verified that it works using kpartx only. r...@sysresccd /root % kpartx -av /dev/virtualmachines/winxphome32 add map virtualmachines-winxphome32p1 (253:22): 0 104840127 linear /dev/virtualmachines/winxphome32 63 r...@sysresccd /root % cd /dev/mapper r...@sysresccd /dev/mapper % ls *winxphome32* virtualmachines-winxphome32 virtualmachines-winxphome32p1 r...@sysresccd /dev/mapper % ls -al *winxphome32* brw-rw---- 1 root disk 253, 0 2009-11-12 15:49 virtualmachines-winxphome32 brw-rw---- 1 root disk 253, 22 2009-11-12 18:47 virtualmachines-winxphome32p1 r...@sysresccd /dev/mapper % ls -al *winxphome32* brw-rw---- 1 root disk 253, 0 2009-11-12 15:49 virtualmachines-winxphome32 brw-rw---- 1 root disk 253, 22 2009-11-12 18:47 virtualmachines-winxphome32p1 r...@sysresccd /dev/mapper % fdisk -l virtualmachines-winxphome32 Disk virtualmachines-winxphome32: 53.7 GB, 53687091200 bytes 255 heads, 63 sectors/track, 6527 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x2b362b35 Device Boot Start End Blocks Id System virtualmachines-winxphome32p1 * 1 6526 52420063+ 7 HPFS/NTFS Without the losetup and the corresponding overhead, it will speed up cloning of my virtual machines within LVs. -- 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.unive...@gmail.com Mobile Phone (Starhub Prepaid): +65-8369-2618 Street: Bedok Reservoir Road Country: Singapore
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