4 4 3 Tigon:KVM QEMU Backup
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SEP sesam provides efficient data protection for libvirt-based KVM virtualization by integrating into the libvirt layer of the virtualization system. Introduced in SEP sesam 4.4.3 Tigon, KVM/QEMU integration allows you to back up KVM/QEMU virtual machines on single host systems. Supported backup types are FULL and COPY.
Example configurations are single virtualization hosts running Debian, CentOS or SLES-based distributions in single instance setups that are used to virtualize systems using QEMU and libvirt. Note that high-level applications, such as OVIRT, and other cloud-based solutions, such as OpenNebula or Cloudstack are not supported.
SEP sesam KVM/QEMU integration advantages
- Online backup of running virtual machines using snapshot technology.
- Online backup of virtual machine configuration.
- Restore of complete virtual machines and configuration.
- Restore of virtual machine configuration.
- Restore into new virtual machine instances.
To ensure error-free operation of SEP sesam and improve performance, make sure that the following conditions are met:
- Check the support matrix for the list of supported KVM/QEMU versions.
- Make sure that you have configured KVM/QEMU with SEP sesam properly as described in the next step.
Configuring SEP sesam Client on KVM/QEMU host
In order to be able to backup the virtual machines from your KVM/QEMU hypervisor, download and install the SEP sesam Client for your distribution in use. As of SEP sesam 4.4.3 Tigon, SEP sesam client already contains all needed components for backing up the KVM/QEMU virtual machines.
The KVM/QEMU host system has to be configured as regular client in the SEP sesam Server and backup of regular files from the KVM/QEMU hypervisor must be functional.
Configuring KVM/QEMU backup task
Configuring a KVM/QEMU backup on a SEP sesam Server involves creating a KVM/QEMU backup task, setting up a backup schedule (specifying when you want to back up your data) and linking the schedule to a backup event (specifying how to back up the data and where to back it up to). For general details on backup configuration and prerequisites, see Standard Backup Procedure. However, configuring an KVM/QEMU backup differs slightly from the standard procedure and requires some KVM/QEMU-specific steps, which are described below.
|The virtual machine that you want to back up must not have any defined internal or external snapshots.|
- From Main Selection -> Tasks -> By clients, select KVM/QEMU client and click New backup task. The New backup task window opens.
- Select the Source. Click the Browse button (big arrow) and select the KVM virtual machine that you want to back up from the listed virtual machines detected on the host system. By selecting the source, the backup type and task name are set automatically.
- If you want to define other options (such as pre/post backup and restore commands, set encryption or compress data (do not use this option if you want to restore a single file!), consolidate individual tasks under a specific task group, assign a task to the schedule), click the corresponding tabs in the New backup task window.
Click OK to create the task.
- If you want to start the newly created task immediately, right-click the name of the task and click Immediate Start. If you want to create a periodic backup, you have to create a schedule for your backup task: Click New schedule under Main Selection -> Scheduling -> Schedules and set up a schedule. For more details, see Creating a schedule.
- Once you have configured a schedule, you must create a new backup event for it. For general information on creating a backup event, see Creating a backup event. Note that only FULL or COPY backups of KVM virtual machines are supported.
|You can also add your backup task to an existing schedule by double-clicking the backup task, selecting the tab Schedules and adding it to one or more schedules. Additionally, you can group your backup tasks to task groups. For details, see Adding a Task to the Task Group.|
You can view the status of your backup jobs by selecting Last backup state in the Main Selection window. The backup status overview provides detailed information on the last run of backup jobs, including the task name, start and stop time of the last backup, backup type, data size, throughput, assigned media pool, etc.
DRBD or direct attached storage
By default, SEP sesam KVM/QEMU module only supports virtual machines with default QCOW2 or RAW devices placed in the regular file system of the virtualization host. If you want to back up a virtual machine with a direct attached storage, a few additional steps are required.
- To snapshot a device with direct attached storage (ISCSI LUN, DRBD device) of a virtual machine, the snapshot data must be put to the disk of the hypervisor during backup. Having only internal snapshot is not sufficient for correct back up of the virtual machines disks.
- In the GUI, add the following option to the second tab Options in the Save options' field:
By adding this option, SEP sesam KVM/QEMU will place the external snapshot of the direct attached storage into this directory. Note that in this configuration it is only possible to backup the whole LUN device with non-used blocks.
Merging and deleting left over snapshots
In case a backup may fail and a snapshot ist left behind, either use the graphical "virt-manager" tool to delete the snapshot or virsh like in the following examples:
Step 1: list available snapshots for domain:
user@hypervisor:~$ virsh snapshot-list <domain-name> Name Creation Time State ------------------------------------------------------------ Sesam_SF20173828282@XXXX 2017-07-06 08:15:11 +0200 disk-snapshot
as seen in the example there exists one leftover snapshot for this virtual machine.
Step 2: list virtual disks of domain:
user@hypervisor:~$ virsh domblklist <domain-name> Target Source ------------------------------------------------ sda /path/to//Sesam_SF20173828282@XXXX.snapshot
Step 3: for each device that refers to a sesam snapshot start an block commit to merge the snapshot:
user@hypervisor:~$ virsh blockcommit <domain-name> sda --active --verbose --pivot Block Commit: [100 %] Successfully pivoted
Step 4: confirm the device has now switched to the original disk device:
user@hypervisor:~$ virsh domblklist <domain-name> Target Source ------------------------------------------------ sda /my/original/base.img
Step 5: Delete snapshot metadata information:
user@hypervisor:~$ virsh snapshot-delete <domain-name> --metadata --snapshotname Sesam_SF20173828282@XXXX Domain snapshot sesam_snapshot deleted
Step 6: Delete snapshot file:
user@hypervisor:~$ rm /path/to//Sesam_SF20173828282@XXXX.snapshot