On Fri, Oct 12, 2012 at 9:26 PM, Lukas Laukamp <lukas@xxxxxxxxxx> wrote: > Am 12.10.2012 21:13, schrieb Stefan Hajnoczi: > >> On Fri, Oct 12, 2012 at 8:14 PM, Lukas Laukamp <lukas@xxxxxxxxxx> wrote: >>> >>> Am 12.10.2012 13:36, schrieb Stefan Hajnoczi: >>> >>>> On Fri, Oct 12, 2012 at 12:50 PM, Lukas Laukamp <lukas@xxxxxxxxxx> >>>> wrote: >>>>> >>>>> Am 12.10.2012 12:47, schrieb Stefan Hajnoczi: >>>>> >>>>>> On Fri, Oct 12, 2012 at 12:16 PM, Lukas Laukamp <lukas@xxxxxxxxxx> >>>>>> wrote: >>>>>>> >>>>>>> Am 12.10.2012 12:11, schrieb Stefan Hajnoczi: >>>>>>> >>>>>>>> On Fri, Oct 12, 2012 at 11:17 AM, Lukas Laukamp <lukas@xxxxxxxxxx> >>>>>>>> wrote: >>>>>>>>> >>>>>>>>> Am 12.10.2012 10:58, schrieb Lukas Laukamp: >>>>>>>>> >>>>>>>>>> Am 12.10.2012 10:42, schrieb Stefan Hajnoczi: >>>>>>>>>>> >>>>>>>>>>> On Fri, Oct 12, 2012 at 08:52:32AM +0200, Lukas Laukamp wrote: >>>>>>>>>>>> >>>>>>>>>>>> I have a simple user question. I have a few LVM based KVM guests >>>>>>>>>>>> and >>>>>>>>>>>> wan't to backup them to files. The simple and nasty way would be >>>>>>>>>>>> to >>>>>>>>>>>> create a complete output file with dd, which wastes very much >>>>>>>>>>>> space. >>>>>>>>>>>> So I would like to create a backup of the LVM to a file which >>>>>>>>>>>> only >>>>>>>>>>>> locates the space which is used on the LVM. Would be create when >>>>>>>>>>>> the >>>>>>>>>>>> output file would be something like a qcow2 file which could be >>>>>>>>>>>> also >>>>>>>>>>>> simply startet with KVM. >>>>>>>>>>> >>>>>>>>>>> If the VM is not running you can use "qemu-img convert": >>>>>>>>>>> >>>>>>>>>>> qemu-img convert -f raw -O qcow2 /dev/vg/vm001 >>>>>>>>>>> vm001-backup.qcow2 >>>>>>>>>>> >>>>>>>>>>> Note that cp(1) tries to make the destination file sparse (see >>>>>>>>>>> the >>>>>>>>>>> --sparse option in the man page). So you don't need to use >>>>>>>>>>> qcow2, >>>>>>>>>>> you >>>>>>>>>>> can use cp(1) to copy the LVM volume to a raw file. It will not >>>>>>>>>>> use >>>>>>>>>>> disk space for zero regions. >>>>>>>>>>> >>>>>>>>>>> If the VM is running you need to use LVM snapshots or stop the VM >>>>>>>>>>> temporarily so a crash-consistent backup can be taken. >>>>>>>>>>> >>>>>>>>>>> Stefan >>>>>>>>>>> -- >>>>>>>>>>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>>>>>>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>>>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Hello Stefano, >>>>>>>>>> >>>>>>>>>> thanks for the fast reply. I will test this later. In my case now >>>>>>>>>> it >>>>>>>>>> would >>>>>>>>>> be a offline backup. For the online backup I think about a >>>>>>>>>> seperated >>>>>>>>>> system >>>>>>>>>> which every day makes incremental backups and once a week a full >>>>>>>>>> backup. >>>>>>>>>> The >>>>>>>>>> main problem is, that the systems are in a WAN network and I need >>>>>>>>>> encryption >>>>>>>>>> between the systems. Would it be possible to do something like >>>>>>>>>> this: >>>>>>>>>> create >>>>>>>>>> the LVM snapshot for the backup, read this LVM snapshot with the >>>>>>>>>> remote >>>>>>>>>> backup system via ssh tunnel and save the output of this to qcow2 >>>>>>>>>> files >>>>>>>>>> on >>>>>>>>>> the backup system? And in which format could be the incremental >>>>>>>>>> backups >>>>>>>>>> be >>>>>>>>>> stored? >>>>>>>> >>>>>>>> Since there is a WAN link it's important to use a compact image >>>>>>>> representation before hitting the network. I would use qemu-img >>>>>>>> convert -O qcow2 on the host and only transfer the qcow2 output. >>>>>>>> The >>>>>>>> qcow2 file does not contain zero regions and will therefore save a >>>>>>>> lot >>>>>>>> of network bandwidth compared to accessing the LVM volume over the >>>>>>>> WAN. >>>>>>>> >>>>>>>> If you are using rsync or another tool it's a different story. You >>>>>>>> could rsync the current LVM volume on the host over the last full >>>>>>>> backup, it should avoid transferring image data which is already >>>>>>>> present in the last full backup - the result is that you only >>>>>>>> transfer >>>>>>>> changed data plus the rsync metadata. >>>>>>>> >>>>>>>> Stefan >>>>>>>> -- >>>>>>>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>>>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>>> >>>>>>> >>>>>>> Hello Stefan, >>>>>>> >>>>>>> the rsync part I don't have understood fully. So to create a qcow2 on >>>>>>> the >>>>>>> host, transfer this to the backup server will result in the weekly >>>>>>> full >>>>>>> backup. So do you mean I could use rsync to read the LVM from the >>>>>>> host, >>>>>>> compare the LVM data with the data in the qcow2 on the backup server >>>>>>> and >>>>>>> simply transfer the differences to the file? Or does it work on >>>>>>> another >>>>>>> way? >>>>>> >>>>>> When using rsync you can skip qcow2. Only two objects are needed: >>>>>> 1. The LVM volume on the host. >>>>>> 2. The last full backup on the backup client. >>>>>> >>>>>> rsync compares #1 and #2 efficiently over the network and only >>>>>> transfers data from #1 which has changed. >>>>>> >>>>>> After rsync completes your full backup image is identical to the LVM >>>>>> volume. Next week you can use it as the "last" image to rsync >>>>>> against. >>>>>> >>>>>> Stefan >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>> >>>>> >>>>> So I simply update the full backup, which is simply a raw file which >>>>> get >>>>> mounted while the backup? >>>> >>>> The image file does not need to be mounted. Just rsync the raw image >>>> file. >>>> >>>> Stefan >>> >>> >>> I tested the qemu-img command now, but it does not do that what I want. I >>> have a VM with a 5GB disk, this disk is not allocated with 1GB of data. >>> When >>> I do the convert command the output is a 5GB qcow2 disk. What do I have >>> to >>> do to get a qcow2 file with only the allocated space/data from the LVM? I >>> also tried the -c option of qemu-img convert but the result was nearly >>> the >>> same. >> >> Please show the exact command-lines you are using and the qemu-img >> info <filename> output afterwards. >> >> Stefan >> -- >> To unsubscribe from this list: send the line "unsubscribe kvm" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Hello, > > the VM is called mailer and I used this command: qemu-img convert -f raw -c > -O qcow2 /dev/vmdisks/mailer ./vmachines/mailer.qcow2 > > Im on the /mnt dir because it's a seperate HDD with the folder vmachines. > > Thats the output of qemu-img info: > > image: ./vmachines/mailer.qcow2 > file format: qcow2 > virtual size: 5.0G (5368709120 bytes) > disk size: 4.1G > cluster_size: 65536 > > I checked the info of the fs inside the guest. The / partition is 4,7GB big > and 1,2GB are used. The fs is ext3. I wonder if you see better results without the -c option. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
