server2.example.com<\/span>) at the same time. This is a great method to clone VMs.<\/p>\n2 Preparing The OpenVZ Servers<\/h3>\n
First we must install vzdump and rsync which is a dependency. On Debian, the command is as follows:<\/p>\n
server1\/server2:<\/p>\n
apt-get install vzdump rsync<\/p>\n
3 Creating A Backup Of A VM<\/h3>\n
(This chapter is for server1 only!)<\/p>\n
On server1.example.com<\/span>, I want to create a backup of my VM with the VEID 102<\/span>. Take a look at<\/p>\nman vzdump<\/p>\n
to learn how to use vzdump<\/span>.<\/p>\nTo back up all VMs on your server, you’d use something like<\/p>\n
vzdump –compress –dumpdir \/home\/backup –stop –all<\/p>\n
–compress<\/span> means: compress the dump file (results in a .tgz<\/span>).<\/p>\n–dumpdir<\/span> specifies the directory in which you want to store the dump. If you don’t specify a dumpdir, it defaults to \/vz\/dump<\/span> or \/var\/lib\/vz\/dump<\/span> (depends on your distribution).<\/p>\n–stop<\/span> stops the VM, creates the backup, and starts it again afterwards. Your VM can be down a few minutes if you use –stop<\/span>. A faster solution would be to use…<\/p>\n–suspend<\/span>: it suspends the VM; the VM is then copied via rsync to a temporary directory. The VM gets resumed right afterwards so that it’s down only a few seconds, and then the dump is created using the copy in the temporary directory. I recommend to use this one if you can’t afford long downtimes.<\/p>\nYou can as well leave out –stop<\/span> and –suspend<\/span> and dump a running VM. In most cases this makes no problem, but it is possible that the dump is inconsistent, so be warned!<\/p>\n–all<\/span> creates a dump of all available VMs. If you want to dump only a specific VM, replace –all<\/span> with the VEID<\/span> of the VM.<\/p>\nTo create a dump of our VM 102<\/span> in \/home\/backup<\/span> and stop the VM during the backup, use<\/p>\nvzdump –compress –dumpdir \/home\/backup –stop 102<\/p>\n
To create a dump in the default directory (\/vz\/dump<\/span> or \/var\/lib\/vz\/dump<\/span>), use<\/p>\nvzdump –compress –stop 102<\/p>\n
The output could look as follows:<\/p>\n
server1:\/vz\/dump# vzdump –compress –stop 102
\nINFO: starting backup for VPS 102 (\/var\/lib\/vz\/private\/102)
\nINFO: starting first sync \/var\/lib\/vz\/private\/102 to \/var\/lib\/vz\/dump\/tmp9009
\nINFO: stopping vps
\nStopping container …
\nContainer was stopped
\nContainer is unmounted
\nINFO: final sync \/var\/lib\/vz\/private\/102 to \/var\/lib\/vz\/dump\/tmp9009
\nINFO: restarting vps
\nStarting container …
\nContainer is mounted
\nAdding IP address(es): 192.168.0.102
\nSetting CPU units: 1000
\nConfigure meminfo: 65536
\nSet hostname: test.example.com
\nFile resolv.conf was modified
\nContainer start in progress…
\nINFO: vps is online again after 15 seconds
\nINFO: Creating archive ‘\/var\/lib\/vz\/dump\/vzdump-102.tgz’ (\/var\/lib\/vz\/dump\/tmp9009\/102)
\nTotal bytes written: 340428800 (325MiB, 11MiB\/s)
\nINFO: backup for VPS 102 finished successful (1.37 minutes)
\nserver1:\/vz\/dump#<\/p>\n
To not stop, but suspend the VM, use<\/p>\n
vzdump –compress –suspend 102<\/p>\n
This is a sample output:<\/p>\n
server1:~#\u00a0vzdump\u00a0–compress\u00a0–suspend\u00a0102
\nINFO:\u00a0starting\u00a0backup\u00a0for\u00a0VPS\u00a0102\u00a0(\/var\/lib\/vz\/private\/102)
\nINFO:\u00a0starting\u00a0first\u00a0sync\u00a0\/var\/lib\/vz\/private\/102\u00a0to\u00a0\/var\/lib\/vz\/dump\/tmp10842
\nINFO:\u00a0suspend\u00a0vps
\nSetting\u00a0up\u00a0checkpoint…
\nsuspend…
\nget\u00a0context…
\nCheckpointing\u00a0completed\u00a0succesfully
\nINFO:\u00a0final\u00a0sync\u00a0\/var\/lib\/vz\/private\/102\u00a0to\u00a0\/var\/lib\/vz\/dump\/tmp10842
\nINFO:\u00a0resume\u00a0vps
\nResuming…
\nINFO:\u00a0vps\u00a0is\u00a0online\u00a0again\u00a0after\u00a04\u00a0seconds
\nINFO:\u00a0Creating\u00a0archive\u00a0‘\/var\/lib\/vz\/dump\/vzdump-102.tgz’\u00a0(\/var\/lib\/vz\/dump\/tmp10842\/102)
\nTotal\u00a0bytes\u00a0written:\u00a0340428800\u00a0(325MiB,\u00a024MiB\/s)
\nINFO:\u00a0backup\u00a0for\u00a0VPS\u00a0102\u00a0finished\u00a0successful\u00a0\u00a0(1.57\u00a0minutes)
\nserver1:~#<\/p>\n
After the backup, take a look at the dump directory…<\/p>\n
ls -l \/vz\/dump\/<\/p>\n
… and you should see a .tgz<\/span> file:<\/p>\nserver1:~#\u00a0ls\u00a0-l\u00a0\/vz\/dump\/
\ntotal\u00a0147864
\n-rw-r–r–\u00a01\u00a0root\u00a0root\u00a0\u00a0\u00a0\u00a0\u00a0\u00a01170\u00a02008-11-20\u00a017:40\u00a0vzdump-102.log
\n-rw-r–r–\u00a01\u00a0root\u00a0root\u00a0151249685\u00a02008-11-20\u00a017:40\u00a0vzdump-102.tgz
\nserver1:~#<\/p>\n
You can now copy the dump to the other OpenVZ server, e.g. with scp (this copies \/vz\/dump\/vzdump-102.tgz<\/span> to the \/home<\/span> directory on server2.example.com<\/span>):<\/p>\nscp \/vz\/dump\/vzdump-102.tgz root@192.168.0.101:\/home<\/p>\n
4 Restoring A VM<\/h3>\n
(This chapter is for server2 only!)<\/span><\/p>\nOn server2.example.com<\/span>, you can now restore the VM as follows…<\/p>\nvzdump –restore \/home\/vzdump-102.tgz 250<\/p>\n
… where 250<\/span> is the new VEID of the restored VM – you can use any VEID that is unused on server2.example.com<\/span> – you could even use 102<\/span> again if it is unused on server2.example.com<\/span>.<\/p>\nIf you don’t want to modify the settings of the VM (e.g. IP address, hostname), you can start it now, but please make sure that the original VM is stopped on server1.example.com<\/span> because otherwise the IP addresses conflict:<\/p>\nvzctl start 250<\/p>\n
If you want to run both VMs (the original one and the clone) at the same time, you must change the IP address and hostname of the clone<\/span> before you start it.<\/p>\nTo set a new hostname, run sonething like this:<\/p>\n
vzctl set 250 –hostname test2.example.com –save<\/p>\n
To set a new IP address, we must first delete the original one…<\/p>\n
vzctl set 250 –ipdel 192.168.0.102 –save<\/p>\n
… and then set a new one:<\/p>\n
vzctl set 250 –ipadd 192.168.0.250 –save<\/p>\n
Afterwards we can start the clone:<\/p>\n
vzctl start 250<\/p>\n