Thank you for your advice! Is it called LVM snapshot?
-- 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 2009/11/12 Veli-Pekka Kestilä <fed...@guagua.fi> > 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. >> >> # losetup /dev/loop1 /dev/virtualmachines/windows7-x64 >> windows7-x64 is the logical volume. >> # kpartx -av /dev/loop1 >> >> Then I would see the partitions of the virtual machine within a logical >> volume, like so: >> >> /dev/mapper/loop1p1 >> /dev/mapper/loop1p2 >> /dev/mapper/loop1p3 >> >> Now that I can access the partitions of the virtual machine within a >> logical volume, I can use partimage or fsarchiver to backup the partitions >> (provided the filesystem is supported by the archiver). >> >> But the problem is that I can only backup/clone the filesystems of my >> virtual machine within a logical volume. I can't backup the Master Boot >> Record (MBR) of the virtual machine within a logical volume. For example, >> >> 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. >> > You can do dd if=/dev/dev/loop1 of=mbr.dha bs=512 count=1 to make the copy > of the boot block. > > >> I would like to know how to backup and also restore the MBR of my virtual >> machine/guest operating system/domU within a logical volume because the >> losetup and kpartx procedure only allows me access to the partitions, not >> the MBR. A complete backup of a virtual machine (and also a bare metal >> machine) includes the MBR and all filesystems. >> >> If there is a catastrophic failure with my logical volumes containing >> domUs, I would like to >> >> 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 >> >> Of these steps you can recreate 1,2,3 and 4 just by keeping records of > their parameters and using normal fdisk, pvcreate, vgcreate and lvcreate > commands. > > For the things inside of lvm you can use losetup to make the loopback > device out of the lv where you want to install the quest operating system > and then recreate mbr from the file. Problem probably is how to recreate the > filesystems if your backup software cannot do it. Also with windows > protected system files can be a problem if backup software doesn't support > them. > > One thing you could of course do is to make the system restore backup > inside of the DomU when it's running. And then boot new DomU when starting > up and use the system backup to restore. (of course this is still more work > that pure dd from one place to another.) > > Problem is that everything else than using dd can have it fair share of > problems. If the domU can't be offline too long, you could allocate more > space and use the lvm:s instant cloning features (can't remember the name > just now. ) and then use dd with gzip or bzip to make the backup from this > clone to keep the space requirements minimum for the stored copies. And have > minimum disruption for the DomU. > > -vpk > > -- > Fedora-xen mailing list > Fedora-xen@redhat.com > https://www.redhat.com/mailman/listinfo/fedora-xen >
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