Skip to content

Storage-based VM snapshots on KVM #153

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Apr 21, 2022
Merged

Storage-based VM snapshots on KVM #153

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
9c0f1ea
[WIP] Storage-based VM snapshots on KVM
slavkap Sep 16, 2020
6e62e4a
Removed information for QCOW2 support
slavkap Apr 12, 2022
bd0242d
Fix reference
slavkap Apr 21, 2022
6f0f8cd
Fix section
slavkap Apr 21, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 25 additions & 1 deletion source/adminguide/virtual_machines.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -814,14 +814,37 @@ like many other resources in CloudStack.

KVM supports VM snapshots when using NFS shared storage. If raw block storage
is used (i.e. Ceph), then VM snapshots are not possible, since there is no possibility
to write RAM memory content anywhere.
to write RAM memory content anywhere. In such cases you can use as an alternative
`Storage-based VM snapshots on KVM`_


If you need more information about VM snapshots on VMware, check out the
VMware documentation and the VMware Knowledge Base, especially
`Understanding virtual machine snapshots
<http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&externalId=1015180>`_.


.. _`Storage-based VM snapshots on KVM`:

Storage-based VM snapshots on KVM
---------------------------------

.. note::
For now this functionality is limited for NFS and Local storage.

CloudStack introduces a new Storage-based VM snapshots on KVM feature that provides
crash-consistent snapshots of all disks attached to the VM. It employs the underlying storage
providers’ capability to create/revert/delete disk snapshots. Consistency is obtained by freezing
the virtual machine before the snapshotting. Memory snapshots are not supported.

.. note::
``freeze`` and ``thaw`` of virtual machine is maintained by the guest agent.
``qemu-guest-agent`` has to be installed in the VM.

When the snapshotting is complete, the virtual machine is thawed.

You can use this functionality on virtual machines with raw block storages (E.g. Ceph/SolidFire/Linstor).

Limitations on VM Snapshots
---------------------------

Expand Down Expand Up @@ -857,6 +880,7 @@ Configuration Description Type
====================== ========================
vmsnapshots.max The maximum number of VM snapshots that can be saved for any given virtual machine in the cloud. The total possible number of VM snapshots in the cloud is (number of VMs) \* vmsnapshots.max. If the number of snapshots for any VM ever hits the maximum, the older ones are removed by the snapshot expunge job
vmsnapshot.create.wait Number of seconds to wait for a snapshot job to succeed before declaring failure and issuing an error.
kvm.vmstoragesnapshot.enabled For live snapshot of virtual machine instance on KVM hypervisor without memory. Requieres qemu version 1.6+ (on NFS or Local file system) and qemu-guest-agent installed on guest VM
====================== ========================


Expand Down