[cloudstack-documentation] 01/01: Update storage.rst

[an...@apache.org]

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andrijapanic pushed a commit to branch kvm-snapshot-explanation
in repository https://gitbox.apache.org/repos/asf/cloudstack-documentation.git

commit a47be7eb30301dad109af8eb1e7da0acf1178ea9
Author: Andrija Panic <45...@users.noreply.github.com>
AuthorDate: Wed May 6 16:00:18 2020 +0200

    Update storage.rst
---
 source/adminguide/storage.rst | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/source/adminguide/storage.rst b/source/adminguide/storage.rst
index 1254931..70a8304 100644
--- a/source/adminguide/storage.rst
+++ b/source/adminguide/storage.rst
@@ -679,6 +679,20 @@ How to Snapshot a Volume
 
 #. Click the Snapshot button. |SnapshotButton.png|
 
+KVM volume Snapshot specifics
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In recent CloudStack versions, by default, a volume snapshots for a running VM is disabled
+due to a possible volume corruption that can occur while volume snapshot is
+deleted. To enable making a volume snapshots while the VM
+is running, the global setting 'kvm.snapshot.enabled' must be set to 'True'.
+The way the volume snapshot is now created has been changed. 
+Under the hood, first, a full VM snapshot is taken - this means that during the taking of
+the VM snapshot the VM will be in the "Paused" state (while RAM memory is being written to the
+QCOW2 file), which means that VM will be unavailable from the network point of view.
+When the VM snapshot is created, VM is unpaused/resumed, the single volume snapshot is exported
+to the Secondary Storage, and then the VM snapshots is removed from the VM.
+
 
 Automatic Snapshot Creation and Retention
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~