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Pre-requisite: EWC - OpenStack Command-Line client |
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Foreword
Before restoring resources in OpenStack, it's important to understand the difference between three primary methods:
- Intance Snapshots (Glance): These capture the entire virtual machine, including the operating system, applications, and configuration. Instance snapshots are useful for cloning VMs, creating templates, or disaster recovery scenarios. They're managed through the Glance service.
- Volume Snapshots (Cinder): These are delta copies of the block storage volumes. Volume snapshots are not full copies and rely on the original volume for restoration, so they are mostly useful for accident recovery. They're managed through the Cinder service.
- Volume Backups (Cinder): These are point-in-time copies of block storage volumes. Volume backups preserve the data within a volume and can be used to restore the volume to the exact state it was in when backed up. They're ideal for data recovery and are managed through the Cinder service.
Choose the appropriate method based on your recovery needs: instance snapshots for full system recovery or replication, volume snapshots for accident prevention and recovery or volume backups for full data security and recovery.
Furthermore, there are two different restoration methods, according to whether the restoration replaces an existing resource or not:
- In place restoration: the snapshot or backup replaces an existing instance or volume. This is typically useful when data in the original resource has been corrupted and it is necessary to perform a reset to a past state, as stored in the snapshot or backup.
- New copy restoration: a new resource of the type, instance or volume, is created with the snapshot or backup as its base. This method is useful to copy or migrate resources as well as to recover from catastrophic failures.
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| Before starting make sure you are in the machine where you configured openstack client, have the required openstack credentials and you can run openstack commands as described in EWC - OpenStack Command-Line client |
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| When creating The restoration of backups or snapshots of VMs and volumes , it is highly recommended that the following command are must be run outside from said VMs and volumes. Doing so from within may cause corrupted backups or snapshots, specially in the case of in-place restoration, as the existing resource is completely replaced. |
Restoring VMs and Volumes
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Restoration of VM snapshots Anchor
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RestoreVMSnapshots
| RestoreVMSnapshots |
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RestoreVMSnapshots
| RestoreVMSnapshots |
OpenStack provide a mechanism to replace the underlying disk of an existing VM with an image without creating a new VM instance running the following command:
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where
- VM-NAME
<instance>: The name or id of the existing VM - IMAGE
<image_IDsnapshot>: Name or id of the backup snapshot image of the VM you created before
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- previously created
It is worth noting that the underlaying image of the instance
Restoration of Volume SnapshotsAnchor RestoreVolumeSnapshots RestoreVolumeSnapshots
Restoration of Volume BackupsAnchor
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RestoreVolumeBackups
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RestoreVolumeBackups
To restore a backup to a new volume, first you need to detach the volume from the VM:
ssh into your VM
become root
unmount the
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volume
sudo umount --verbose <path-to-volume>
- Then you can restore the backup to the volume with OpenStack (from the machine where you are running Openstack commands):
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